NMR spectra of organogermanium compounds

Nlul SPBCTRA OP DRGANDGERllllllItD! -tINDS. NMR SPECTRA AND IWDD CALCQLATIOIIS

Yoehito

Takeuchi*,

Katsumi

Keiichiro

Department

of

Dgawa

of

Tokyo,

Komaba,

Toshie

Harazono,

Yoshimuta

The College

Chemistry,

The University

Tanaka,

and Shin

7.’

EitnAcYcLoAExAwEs.

OF P-

of

Arts

Heguro-ku,

and Sciences, Tokyo,

Japan

153

(Received m U.S.45 Aprrl 1988)

Abstract 13C nmr spectra of a variety of 1 -phenylgermacyclohexanes indicates that the conformational energy of a phenyl group on germanium 1s essentially zero (0 - 0.1 kcal/mol), in a sharp contrast with that in phenylcyclohexanes. The results are consistent with the heats of formation of phenylgermacyclohexanes calculated by the MNDD method.

In methyl and

the

previous

group

in

conununlcat10n2

73Ge nmr spectroscopy.

trans-

and

indicated

while

group

4G)

or

methyl

axialtfor

trans-4G

and

ring

is

fixed

that

of

cis-4G

the

chemical

latter

with

chemical l(33.1

cis-4G by

Me-4.

is

30.2

shifts

conformational

0 -

-0.2

The

of

in

Me-l

1s

is

the

energy

conclusion of

of

He-l

the

equatorial the

for, Based

a

methyl

in

shifts

remains of the

and

is

32.7

observed the

on

this

effect

of

additivity

germacyclohexanes

is

the

Me-4

shift

shifts

simple

with

while of

chemical

chemical

of

ppm and

identical

conformation(2GQl,

of

He-4

germacyclohexane

trans-4G

the

trans-

and

C-4

essentially If

of

equatorial

cis-3C

shifts of

a

’ 3c

1,4-dlmethylgerma-

indicate

conformation(2GX).

weight-average

was

ster1c

of

difference

germanium

was estimated

interesting

further

energies

of

proposed

by

to

verification

of

his

axial

was He

prediction.

experimental of

0.22

be

phenomenon

methylsilacyclohexane(2S).

preference

to

of Of

13C chemical

carbon

may be assumed

corrected

of

on

chemical

shift

equatorial-IG(4GQ).

parameters

first

of

energy

combination

equatorialffor

identical

2G in

axial

group be

The

former

a

upon

of

Me-

Me-l

of

relation,

estimated

to

be

kcal/rnol.2

calculations

the

of and

methyl

chemical

He-l the

2G

and

the

This

conformational

means

comparison

could

essentially

ppm. The

in of

of

the

cls-4Gl.

or

are

shift

axial-IG(4GXl

that

on germanium

trans-3G

that

ppml

This

a careful

Thus,

the

by

c1s-l,3-dimethylgermacyclohexane(3C12

cyclohexane(4C13 the

we estimated

1 -methylgermacyclohexane(ZC)

did

supported 2GQ

2GX

Duellette’

was

kcal/mol in

in

fact

not,

Hence,

demonstration

by

and

the this

conformation. 7531

molecular

mechanics

I4M2 force The

employed.

preference

predicted hovever,

to of

the where

to by

attempt

best

of

very

unusual

our

the

f ield4 sterlc

axial

isomer.2

Ouellette6 any

for

l-

experimental

knovledge, effect,

and

energy

this i.e.,

is the

7532

Y. TAK~IX-M TV al. As a natural

estimate

the

(SC)

since -

group

is

it

the

measurement

is

well

to

of

3.61

low

that

the

conformational

group

this

in

sharp It

in

2.0

energy contrast

1s of

pointed

involved

in

SC.

3.66

phenylcyclohexane(SC)

kcalfmol

of

a

‘H

that

of

to

estimate

Patterson’

nmr spectra

of

that

Eliel

the

Allinger the dipole

on

and

estimated

to

et al.’ moment

estimated

cis-l-t-butyl-l-

the

and

phenyl

conformational

Manoharan”

showed

cis-4-methyl-1-phenylcyclohexane(BC)

phenyl

with

interest

Thus, based

kcal/mol. of

we attempted

1-phenylgermcyclohexane

group.

the

Tribble’

is

in

Carbish

on

13C nmr spectra

group a

is

methyl

2.07 group

the

conformational

the

conformation

kcalftnol. in

All

these

cyclohexane of

energy

(1.78 a phenyl

in germacyclohexanes.

interesting

Tribble’

SC

investigation,

group

methyl

is

based and

in

temperature

on germanium Another

a

energy

kcal/mol

group

the

kcal/mol) .’ ’

that

than

Allinger

a phenyl

are

of

phenyl

4-(p-chlorophenyl)cyclohexanone. be

from values

a

established larger

phenylcyclohexane. energy

of

conformational

of

energy

extension

energy

considerably

estimated the

and essential

steric

out Thus,

aspect that of

ariees

rotational the

equatorial

in

isomerism isomer

about of

SC,

the the

of

SC.

parallel

Vans-3

cls-8

trans-8

trana-7

Vans-9

Vans-10

Me Me

72 7

M\

c : M=C S : M=SI

MO

11

G : M=Ge

Allinger

Ce--C(ipso)

and

bond isomer(

1s

SCQ)

1533

NMR speclraof organoprmanlumcompound~VII in

stable

C-l--H-l

the

C-l--H-l

the

which

more

(by

bond

axial

is

of

conforaert

between

ortho

cyclohexane This

SC,

the

rotational

is

not

the

much

hexane.

Eliel

the

conformer

with

axial

contrary

phenyl does

phenyl

the

the

where

the

enough,

for

stable

strong

the

than

interaction

syn-axial

hydrogens

of

hold

reported

for energy

1 -methyl-l

-

that

axial

in

and

of

a

phenyl

3-phenyl-3,5,5-

Anteunis

et

a1.13

4-methyl-4-phenyl-l,l-dlmethoxycyclo-

showed

simple

more the

however,

remains

for

methyl-axial

and

to

conformational

al.12

group

phenomenon

substantially

1).

the

et

1 is

due

group

not,

that

methyl-equatorial

to

isomer(SCX’ is

is

Interestingly

ring.

This

ring

conformer(SCQ’)

by

13C

nmr

spectra

that

in

phenyl

group

(6CQX)

predominates

phenyl

group

(6CXQ)

(The

prediction

based

on the

6C

the

over

ratio

is

conformational

the

ca

3:l)

energy

of

1 groups.

Allinger

and Tribble’

conformatlon geminal

of

the

methyl

introduction group

aromatic

Shapiro

I4anoharan”

aromatic

conformer(Fig. sense

and

the

perpendicular

kcal/mol. axial

the

same

equatorial

is

the

the

with

individua

of

Thus,

conformer which

the

preference

additive.

to

the

perpendicular 1.56

In

trimethylcyclohexanone reported

to

perpendicular

phenylcyclohexane(6C) group

parallel than

by

SCX)

hydrogen8 in

is

kcal/mol)

perpendicular

isomer

parallel

bond

3.92

is

phenyl

substituent,

of

most

argued

axial

geminal

stable

in

that group

this is

whereas methyl

the

comes about

not

perturbed

considerable

into

the

most

lqustortal

of

occurs

phenylcyclohcxane

conformation(Fig

stable

introduction

perturbation

equatorial

perpendicular

because by the

whose

a

upon phcnyl

1).

aXW

C:M=C Q:M=Cl.

A

5 (R = H) 6 (R - Me)

is

that

D

Q' XQ’

X’ QX’

pbenylcyclohsxanes the

preference

C

of

longer the

and phenylge~cyclohe=n~s

Ce--C

phenyl

bond

group,

length and

the

will

affect

difference

the in

the

preference.

The most phenyl

of

expected

conformational rotational

Q XQ

I

1 mfomtion

Pig. It

B

group

straightforward in

and

a methyl

the

nmr timescale,

SC or

group

in and

procedure

to

decide

6C

is

to

determine

the freeze the

to

assess

conformational the ratio

ring of

the

conformational

preference reversal

of

equatorial/axial

energy

between these

of

a phenyl

compounds

conformers.

on

This

7534

Y. TAKEWIU CI a/

is,

impossible

hovever,

reversal

of

which

the

cooling

alternative, or

C-4

device

freeze

to

the

the

conformational

must

energy

on

germanium.

of

much reduced group

mind,

ring

It

we

of

A t-butyl

any

nmr

potential

method

is

reversal

effectively.

the

alkyl will

SG

and

of

their

trans-

by

and and

Shapiro

physical

and

will this

group

et

many only

of

was and

are

at

previous

requirement.

In

1,3-dimethylall

to

with

the

compare

Details

Experimental

in

1 -phenyl-3-

prepared

also in

a

this

1-Phenyl-1,3,3-

Anteuni5.13

viev

hovever,

With

isomers.

given

the group

geometrical prepared

C-3

when

a phenyl

sufficient. ve

An

successfully

1,4-dimethyl-l-germacyclohexane(lOG1

cis-

al.‘*

properties

alkyl

an

on germanium,

may be

Furthermore,

realize.*

by

that

ring

temperature

vas

hold

than

satisfy

a methyl

of

method

employed

this

introduce

6G.

trimethylgermacyclohexanellG~ obtained

This

for

the

1-phenyl-4-methylgermacyclohexaneO

1-phenylgermacyclo-hexane(9Gl mixture

of

to

barrier can

introduction

larger

certainly

low vlthin

spectrometer

2G2

is

very frozen

that

group

energy

methylgennacyclohexane(7C),

of

remembered

much easy

prepared

to

analysis

be

group

is

apparently be

conformational

which

the

cannot

conformational

lnve5tlgator5.14

methyl

of vhich

attached

and an equally

to

applied

because

germacyclohexane(lG1

of

the

the

as

a

results

preparation

and

section.

DISCUSSIDN 1-PEmVYL.GBRMCYQRS ’ 3C --- NHR SPECTRA---The determined. It cis-

is

clear

isomers

and

He-4

are

also

13C

The chemical

are

of

from 7G

the and

essentially

in

are

in Table

For was

13Cb chemical

He-3

because

trans-

73Gea

Compound

h-1

c-2

c-3

c-4

C-S

C-6

1G 2G trans-3G

131.2 -65.3 -70.9

9.32 12.10 20.66

26.78 25.58 31.97

29.80 29.61 38.26

26.78 25.58 24.61

9.32 12.10 11.00

cis-3G

-60.3

21.75

31.97

38.43

26.12

11.95

trans-4G

-61.5

11.76

34.81

35.27

34.81

11.76

cis-4G

-73.4

10.84

33.51

35.19

33.51

10.84

-69.4 -25.6

11.96 14.26 20.80 19.81 11.09 10.19 22.79

26.13 26.00 31.90 33.37 34.63 33.63 32.46

30.12 30.42 37.92 38.27 35.23 35.02 38.40

26.13 26.00 24.66 25.87 34.63 33.63 25.18

11.96 14.26 10.36 11.34 11.09 10.19 12.91

cis-9G

22.88

32.59

38.57

25.18

13.00

trans-10G

13.08

34.06

35.54

34.06

13.08

cis-1OG

12.82

34.06

35.36

34.06

12.82

11G

20.76

32.34

42.56

27.96

12.44

5: trans-7G cis-7G trans-8G tie-6G trans-9G

-74.9e -74.9'

of

and the

and

identical

shifts

SG-11G

were

1.

1 that

equatorial

situation

phenylgermacyclohexanes

Table

1.

Table

and

data 8C

of

spectra are

identical.

The

identical.

nmr

shifts

Re-4

tie-BG,

with

of

both

C-4

4G.*e3

trans-

and

of

He-3

shifts

chemical

chemical For

7G,

shifts the

C-3

geraacyclohexanes.C He (position)

C-ipso

c-o

-7.01(l) -7.58(l) 27.29(3) -5.28(l) 27.60(3) -5.77(l) 23.70(4) -7.83(l) 23.70(4) 138.00 -4.68(l) 140.90 27.17(3) 141.59 27.610) d 23.49(4) d 23.32(4) 141.46 -6.15(l) d 27.65(3) -2.51(l) 141,20 27.78(3) -3.20(l) 140.89 23.57(4) -6.32(l) 141.20 23.31(4) -2.17(l) 141.97 31.55, 33.33(3)

134.27 133.58 134.57 134.35 134.40 134.27 133.45 133.45 133.40 133.40 133.35

b In ppm relative to internal THIS. In ppm relative to external GefCH 14. 127-128 ppm) were not attempted. The assignments m-C and p-C signa j s (ca. d” The chemical shifts are possibly identical with that of geometric isomers. e The signal was not resolved into two peaks. a

NNR spectra of organogcnnanrum compounds --VII chemical

shift

of

corresponding axial

phenyl

This

for

the

This 6G

in

phenyl

group

relevant is

axial turn

corrected

former.

suggests

that

the

axial of

nuclei This

for.

than in

view

carbon

in

trans-

of

of

the 10

or

can

If

be

if

estimated

to

of

this

the

than due

close

(3

in

should

5C

cis-BG

and

is

large

group

cis-8G. in

field

certainly

energy

a methyl

nucleus

higher is

phenyl

conformational

that

correction

of

cyclohexane.

trans-7G

a

at

This

isomer. y effect

in in

somewhat

cis

The

group

shifts

is

the

reasonable

smaller

carbon

isomer of

phenyl

remains

chemical

the

seems

substantially

is

the

of

value

trans

nucleus

group

modest

shift

the

carbon

7535

5

a

2C.

1.5 ppm.

Ppm)

upfield

the the

in

is

the

correct,

weight-average

substituent from

group

a result,

assumption

be

the

to

phenyl As

the

to

effect

of

of

chemical

4-Me

shifts

of

4-methylgermacyclohexane.3 The shifts and

calculation

of

C-2,6)

equatorial

(0

-

0.1

view

of

methyl “Ge ---

kcal/moll

of

group

in

prevent

the

detectable induced

that

5G

mixture It

group

as

the

chemical

1:l

cd,

zero

of

a

of

the

chemical

C-3,5)

of

axial

conformational

germacyclohexane. energy

(from

shifts

to a nearly

in

conformational

This

phenyl

is

group

energy

surprising over

in

that

of

a

cyclohexanes. attempted

also

to

broadening

was

obsered,

observation

of

signals.

l5

signal, by a phenyl

relative

exists

(from

corresponds

a phenyl

the much larger

NMR SPECI’RA---We

ppm

2:3

cd.

conformers.

exce9sive

An

indicates

or

to

it

seems

group

the

that

is

measure

the

however,

in

Since

the

some

of

these

of

of

In Table

the

are

does

electric

1 the

tetramethylgermane

to

give

field

a

gradient

73Ge chemical

also

SG--1lG.

compounds

tetraphenylgermane

distortion

substantial.

external

73Ge nmr spectra

shifts as

included

in

far

as

available. In

the

chemical

conformational

shifts

spectra

for

chemical

shift

other

observe

SG

the

calculations. trans-

7G,

Hz

and

9G- 11 G,

conclusion

Only

90

ca.

the

germacyclohexanes

the

one

drawn

rather

30 ppm)

or

cis-

broadening

broad

to

isomers was

73Ge from

’ 3C nmr

signal

indicate

was

that

the

could

not

be

resolved.

found

too

excessive

to

signals.

conclusion of

the

drawn

complementary because

of

1 -methylgermacyclohexanes,2*3

supported

half-width

difference

of

4C

mechanics

(the

MNDC CALCULATIONS- --In the

analysis 2G and

lG,

and molecular

observed For

of

conformational

from

nmr

justification. the

calculations

lack

for

of

In

and

to

with

be

of

the

case

the

parameters

compounds

analysis

data

of

SG,

used

germanium

2G,

MM2 in

the

however, MM2 or

bonded

agreement

calculation

to

between

is

this

is

a

good

impossible

any

other

sp2

hybridized

force

field carbon

atom. An obvious the

energies

simplest

of as

compounds

the

SC

basis

6G

would

will

means

Dewar

of

et

parameters such

as

comparison

It

are

to The

tetramethylgermane to

more

published

As

reported

values.

ab

initio Ab

prohibitive

occurred give

involved.

experimental

be

compounds.

be

al.16

MNDO might

stereoisomers

will

in

calculations

initio

to

estimate

calculations

computation

time

for even

if

such the

be used.

MNDO’ 7 calculations.

by

approach

organogermanium

or

set

Recently to

alternative

relevant

some far

give

as fairly

comparison or

the

to

us

parameters that

insight the

into

heats

of

reasonable was,

however,

tetrachlorogermane.

compounds.

the

for

germanium

applicable

formation

calculated

heat

of

the

relative

formation results limited

are

stability

of

concerned,

the

in comparison to

We attempted

simple to

with

the

compounds extend

the

7536

Y. TAIEUCHi Table

2.

Steric

Compound

Staric energy

-31.33 -31.29

Data taken from Relative to the Relative to the heats

of

Table

2.

and

-35.16

which group in

46.3O

in

is

in

sharp of

between

of The

heats

and in

small, field

the of

of

good

agreement

dihedral

estimated

by

MJ42) will

concluded

that

The

of

the

between

R-2

5GQ and

of and

SGX,

line

for

is

the

heats

of

in

the

methyl)

are

negligibly and

and

to

extent. two

force

hence

contrast

between 2GX,

the

than case

the

the

42.8O

Thus,

we

conformers

of

the

(the

difference

the

nmr data.

two is

equatorialof

SG,

the

perpendicular

conformer( with the

reduces

and

isomer

perpendicular of

which

from

ZGQ,

equatorial

formation

identical obtained

This of

is

serious

favorable

the

bond

ZCX,

the

reverse

Ge--C

MNDG is

difference

ZGX(axial

lGf29.2O

formation

ZCQ,

For more

the

by

be.

flattened,

any

the

energy.

for 2.

make the

a

butane

underestimate

difference

fact

to

of

of

by nmr measurements

in

energy

isomer

is

The

result

the

Table

axial

are effectively

with

is

MNDG heat

slightly

longer

R-ortho.

obtained

1.03 of

54.9°.‘o

of

and

the

is

from

angle

estimated

should

by MNDO for

formation

in

it

methyl)

ring

ZCQ,

arises

1C as

2CX to

Thus

conformational

of

which

the

the

in

the

the

of

by are

energy

dihedral value

than

results

calculated

listed

unstable,

effect

the

influence

5GQ

H-3,5

smaller

case,

not

heats

1 while

considerably

in

measure

conformer

one(5GQ’

and

2CX -

necessarily

ZGQ(equatoria1

difference

SC are

parallel

this

of

will

energy

and axial-2Cf2CX)

certainly the

angle

9. 9.

steric

conformational

experimental

respectively.

angle

calculated

axial-

methyl of

some

ref. ref.

and germacyclohexanes

The difference,

underestimate

dihedral

from from

equatorial-2C(2CQ)

discrepancy

to the

with

In

much smaller

be a good

axial

taken taken

with

established

the

kcallmol,

the

the

two conformers

calculations.

of

flattening

formation

-31.29

together

to

ring

Data Data

some cyclohexanes

This UNDO

Thus,

the

formation

-31.33

than

contrast

overestimation

UNDO

four. four.

respectively.

cyclohexane.

cyclohexane.

-13.29 -13.70 -12.70 -13.24

the the

formation

smaller of

-2.85 -2.40 -2.79 -1.88

of

for

of

4.03a 4.61”

of

by

kcal/mol,

tendency

repulsion

2. stable stable

calculations

The M?JDOheats

-36.19

moiety

ref. most most

formation

mechanics

characteristic

is

2GQ 2cx

6GXQ 6GXQ* 6GQX 6GQX’

methyl

to

-36.19 -35.16

2.06’ 0.90= 6.43= o.oo=

kcal/mol,

and

Heat of formation

5GQ SGQ’ 5GX 5GX’

The

can

Compound Steric energy

o.oob 3.92b 5.22b 3.66b

molecular

of

Heat of formation

::* 5cx !icX’

a b c

heat

and the beats of formation crenracvcldrsxaneg(koal/rol).

6.89’ 8.6ga

6cXQ’ 6-X CCQX’

in

and

2cq zcx

6W-z

are

energies

cvclohexanes

al

Cl

SCX’.

SGX’ 1 is This

is

due

steric

interaction

stabler

conformers,

0.06

kcal/moll

which

1 -nEmYL-1 -PHfa?YLGeRIU<3YC~ 13C --- NMR SPECRA--of

its

much

larger

In

6C the

phenyl

conformational

group energy

is

axial in

SC

land

perpendicular)

because

of

the

regardless reduced

steric

interaction

6G.

between

It

was

For

this

of

The

revealing.

of

shifts to

and

cis-1OG

are

at

methyl

From

the

he-1 is

indicate

to

“C

6G and

of

these

of

of

axial,

amounts

the

1OG the

phenyl

and

ppm, which methyl-

isomerf6GQXf.

is

methyl

shifts

axial

that

ratio

a

shifts

equatorial

3.5-3.0 phenyl

cis-

trans-9G

chemical

the

the

and

In

estimated

6G and

a

chemical

i.e.,

methyl-axial is

The

to

6G,

very

lOG,

trans-

where

in

6G were is

for

for

the

trans-10G

9G it

and

revealing.

The

since

estimate

Yet,

the

to

not

characteristic

identical

is smaller

than

the

steric

The

the

ca.

ratio

1:l.

group

very

Both

in

6G

are

sensitive

much

the

conformational

chemical

shifts

requirement

difference

is

conformational

less

two methyl

of

Me-

a methyl

and

this

is

the

for

the

of

be added

the

reduces

case of

the

the

phenyl 6C

interaction

is

a methyl (Table is

is

in

axial. and

1lG the

a

is

region

This

is

phenyl

21 seem

to

not

group

support

6GXQ’ (axial

methyl again

and to

perpendicular

indicate

the

methyl a

and

phenyl).

very

similar

groups.

difference

and perpendicular with

formation

kcal/mol, two

that

ppm)

phenyl

between

(equatorial

the

indicate

He-l(-2.17 the

of

detected

groups.

of

0.5

for

that

of

that

non-additivity

was

Me-3

conformation

6GQX’

than

requirement

shift

in the

species

for

interaction

stable

and

phenyl)

which

signals

MNDC heats The

interest

to

in this case,

between

conclusion.

of

substituted

chemical

Hence

are

system

distinct

syn-axial

that

1lG

1lC

geminally

two

HNDC CALCULATIONS---The

contrast

are

of

the

of

methyl.

unexpected

must

carbon nuclei impossible

is

nearly

shifts

f fxed.

of equatorial

parallel

other it

data.

the

of

energy

perpendicular

and

prove

analoque

time.

which

of

those

as

comparison Me-3,

more

of

6C. group

on germanium.

conformationally

in

equatorial

and

is

and

conformers

and

from

shifts

chemical

conformatlonal

It

of

requirements

6G from

group

germanium

with

germanium

of

phenyl

1OG as well

equatorial. are

groups the

identical

The difference

shifts

environment,

of

The

The

field.

C-3

hence

cis-9G

for

Their

1.

of

remains

on of

methyl

true

9G and

Table

and

population

while

13C chemical

a phenyl

above

He-4

those

lower the

2:3

sufficient

first

a

steric

steric

population is

of

essentially

group

than

qeminal

identical.

The the

and

methyl

chemical

that

in

are

Ue-4,

Me-3

isomerf6GXQ)

ca.

essentially

l

at

phenyl

6GQX:6GX9

to

the field

estimate

equatorial

the

same Is

shifts

stereochemistry

vhere

higher

us to

and

much the

included

and

that

its

resonates

allow

if

nmr chemical

are

C-4

indicate

of Me-l reflect a

‘%I

data

phenyl

see

for 9G, the chemical shifts

Thus,

chemical

parallel to

purpose,

determined.

isomers

the

interest

in

energy

group

is

is

again

which

between

the

rather due

parallel

between small to

the conformations (ea. 0.5

the

phenyl

longer and

kcalfmoil, Ge--C

geminal

bond methyl

groups.

Xn

conclusion

conformational (0

-

0.1

identical the

germacyciohexanes.

group

the

in

longer

that

group ,

Furthermore,

phenyl of

found

a phenyl

Consequently

amounts. effect

have

of

kcal/mol).

perpendicular of

we

energy

5G as Ge --C

in

66

there

is

In

the

bonded

the bond

the is

to

qermacyclohexane germanium

two no

conformers

preference

case with on

the

SC.

is

exist for

This

conformation

ring

negligibly

is

a

in

nearly

parallel

another of

the small or

example

substituted

The support

authors of

Institute

wish

this iu

study.

also

to

the

thank

Partial

Ministry

financial

of

Education

support

by

ASAI

for

the

Germanium

generous Research

acknowledged.

PREPARATION OF FH~Y~G~~~UOHE~E~ ---Preparation of phenylgermacyclohexanef! has been carxed out based on the procedure described in the previous report. Thus, the reaction between the his-Grignard reagent of 1,5-dibromopentane and tetrachlorogermane afforded l,l-dichlorogermacyclohexane in a 40% yield. To the dichloride (17 mm011 in diethyl ether (10 ml1 there was added phenylmagnesium bromide prepared from bromobentene (86 mm011 and magnesium (86 mm011. The mixture was refluxed for two hours, and then decomposed with ice-cold aqueous hydrochloric acid t 2 Xf. The ether extract was dried over anhvdrous calcium chloride, the solvent was removed and the residue was distilled in v ~@UO to give l,l-diphenylqermacyclohexane (2.23 g; 43 $1; b.p. 154-157 OC/3 torr. Bromine (7.5 mmol) was added to diphenylgermacyclohexane (7.5 mmolf in ethylene bromidef40 mi 1 under ref luxing. After refluxing for 30 min., the solvent was removed and the residue was- distilled in vacua to aive 1 -brcmo-?phenylgennacyclohexane (1.94 g; 84 0). b.p. 116-118 ‘C/2 torr. * To lithium aluminum hydride (6.4 mm011 in diethyl ether (50 ml) was added a solution of bromophenylger%acyclohex&ne (6.4 mmoll in diethyl ether (5 ml). The resulting mixture was refluxed for 2h. The mixture was decomposed with ice-water and The workup afforded lextracted with diethyl ether. usual phenylqermacyclohexane(SG) (0.98 9; 69 $),b,p. 128-130 OC/l4 torr. thylphenylgermane C H (CH3fGeBr BrookD:p??lP’ b-p. 139-140 0C/fS6t$rr $~CD$?l~“l.“83”9”;113” 6t;y T?a m~~~~~~~ mm01 in diethyl solution of dibromonethylphenylgermene’(2 ether (120 ml), was added a solution of bis-Grignard reagent prepared from 1,5-dibromopentane (26 mm011 and magnesium (89 mmol). The mixture was further refluxed for another 3 The mixture was decomposed with ice-cold hydrochloric acid (2 Ml, and exhr. tracted with diethyl ether. The ether extract was washed with water, dried over anhydrous calcium chloride and distilled in vacua to afford l-methyl-lphenylgarmacyclohexane (66) (2.71 g;44%1, b.p. 95-97 OC12 torr. The preparation of methylphenylgermacyclohexanes 7G-1lG was carried out in 3-methyl- and 2,2-dimethyl-l,S-dibromoa similar manner starting from 2-, pzntane, respectively. Compounds 7G-10C were obtained as a mixture of transand cis-isomers. Selected physical properties of these phenylgermacyclohexanes are listed in Table 3.

Table

3

Compounds (Formula) 5G

Physical

properties

9612

0.40(3ff,

9,

He-1 )666

113/l 1

0,99(3H,

d,

5~6.0,

4.4l(lfi,

m,

H-l)

8G 73 (Ct2H18Gef

118/6

9G

32

107128

(’ 3H20Ge1 Id;

3g

104,3

2H2oGef ,7

,3513

( Cl 3H22Ge 1 a

Yield

germacyclohexanes(SG-1lG)

6H~90i4tiz;cDc131 yielda b.p. flf (Co/ torrl 69 128/14 4.36(1H, m, H-11

lcl lH1 gGel 66 44 (Cl 2Hl 8Gel 76 53 (Cl 2Rj eGe1

14 (=

of

based

on

He-3)

0.86(3H, d, J=6,OHz, He-31 4.33(1H, m, 1-H)

se Me-l) 1; 0.42(3H, d, J=6,7Hz, He-3); o.P8(3H, 0.32(3H, s, Me-l); 0.40(3H, 8, Me-l) d, 0.8413H, d, J-C.OHz, He-4); O.P0(3H, 0.38t3H, s, Me-l); 0.88(3H, s, Ma-3(axf); l.OO(JH, 8, Me-3(eq)l

0.324 3H, s, O.P6(3H, d,

He-l

the immediate precursor.

J=6.7Hz,

Me-3)

JtC,OHz,

He-41

‘H nmr spectra were recorded with a Varian EM-390 MEASURERENT OF SPECTRA---The solution containing a small amount of tetramethylsilane SpectrometerTs a CDC13 (TRS) as the internal standard. as solutions in CDC13 (1:l v/v) on a The 13C nmr spectra were measured Typical measurement conditions were as JEOL FX-9OQ spectrometer at 22.SOHHz. pulse vidth, 13 ~(40~); spectral width, 2000 Hz; number of scans, 500; follow5: 1 s; data points, 4096. pulseT;i~lqp on the same inGe nmr spectra were recorded for the same solution strument equipped with an NW-IT 1OLF low-frequency insert, operating at 3.10HHr, measurement conditions were as follows: pulse in a 1Omm tube at 3OOC. Typical spectral width, 2000 Hz; number of scans, 5000; pulse delay, 150 s (900); width, 100 ms; data points, 4096. was used as the computation MNDO CALCULATIONS---The one in the ARPAC2’ package we assumed the phenylgermacyclohexanes, For the input geometry2 of program. with standoptimizedtby MM21 structure of 1C to which phenyl and methyl groups The computation was carried out ard bond lengths and bond angles incorporated. by means of Micro VAX II with Ultrix-32 ver. 2.0-l and VAX FORTRAN.

REFERENCES

1.

Part

6.

Y.

Takeuchi,

Y.

Ichikaua,

K.

Tanaka

and N.

Japan, 61, 2875 (1988). Y. Takeuchi, H. Shimoda, K. Tanaka, S. Tomoda,

sot

*

Kakimoto,

Bull.

Chem.

K. Ogawa and H. Suzuki, J. Chem. Sot., Perkin Trans. 2, 7 (19881. 580 (1985). 3. Y. Takeuchi, M. Shlmcda and S. Tomoda, Ragn. Reson. Chem., 23, 395, Department of Chemistry, Indiana University, 4. QCPE Publication Bloomington, IN 47405. R. J. Ouellette, J. Am. Chem. Sot., 94, 7674 (19721. 5. (1974). 6. R. J. Oellette, J. Am. Chem. Sot., 96, 2421 7. N. L. Allinger, J. Allinger, M. A. DaRooqe and S. Greenberg, J. Org. Chem., 27, 4603 (1962). E. W. Carbish, Jr. and D. B.Patterson, J. Am. Chem. Sot., 85, 3228 (19631. 8. N. L. Allinger and H. T. Tribble, Tetrahedron Lett., 3259 (19711. 9. E. L. Eliel and H. Manoharan, J. Org. Chem., 46, 1959 (1981). 10. J. A. Hirsch, in N. L. Allinser and E. L. Eliel. ed.. “TODICS in 11. Stereochemistry,” Vol. 1, Wiley-Interscience, p.i99, i967.‘ 12. 8. L. Shapiro, M. J. Gatusso, N. F. Hepfinger R. L. Shone and W. L. White, Tetrahedron Lett.. 219 (19711. 13. H. de Beule, D. Tbvernier and M. Anteunis, Tetrahedron, 3573 (19741. and D. Kandasamy, J. Org. Chem., 42, 51 (19771; 14. E. L. Eliel H. Booth and J. R. Everett, J. Chem. Sot., Perkin Trans. 2., 255 (19801. T. Harazono and N. Kakimoto, Inorq. Chem., 23, 3835 (19841-Y. 15. Y. Takeuchi, Orcranometallice. 6. 186 (19871. 16. H. J. S. Dewar, C. L. Gradv and E. F. tlealv. W. Thiei, J. Am. Chem. S&.,*99, 4899 (19771: 17. R. J. S. Dewarand 18. P. Razerolles, Bull. Sot. Chim. Fr., 29, 1907 (19621. J. Am. Chem. Sot., 85, 1869 (1963). 19. A. G. Brook and G. C. D. Peddle, 506, Department 20. GAPE Publication of Chemistry, Indiana University, Bloomington, IN 47405

2.