Photoaddition of diethyl oxomalonate to olefins

~~~~~~~~~~~ Letters

h.31,

pp.

2981-2984, 1967. PergamonPress Ltd. Printed in Great Britain.

PF!OTOA~3ITIOPJ OF DIETHYL

OXOKALONATE

y. Hara, Y. Odaira Faculty

TO GLEFIN.5

and S. Tsutsumi

of Engineering,

Osaka University

yivako,jima-ku, Osaka, Japan 70 &rch 1967; in revised form 17 April 1967)

(Qecejvd

Althou;h

lhermal reactions

have been knownl", oxomalonate describe

no report upon the photochemical

with some olefins

reaction

of diethyl

with olefins has been made as ,yet. In this report, we wish to

Lhe photoaddition

reactions

of diethyl

oxomalonate

a-metbylst.yrene or norbornene

as l,l-diphenslethslene, isoprene

oxomalonate

of diethyl

with monoenes

such

and diene:; such as

or 2,3-dimeth,vl-l,'i-butadiene. A solution

of diethyl

oxomalonate

(I) (0.1 mole) and an olefin

(0.2 mole) was irrarliated at 366OA* under nitrogen 40-50 hours until the absorption

pressure

and then the residues

under reduced pressure. by infrared

measurement

and elemental

unreacted

olefins

were chromatographed

The adducts

derivatives

at room temperature

band at 372OA of diethyl

After the irradiation,

disappeared.

oxomalonate

for almost

were removed under reduced

on silica Fe1 or distilled

(III) were characterized

and nuclear magnetic

(II)

resonance

to be oxetane

spectra, molecular

wei;-ht

analysis. co2c2H5

o=c

/C02C2H5

+

;c=c;

-

The results

*

co2c2H5

3C60A

b02C2H5 I

hV

II

III

are listed in Table 1.

Emitted

a solution

litrht from 1 kw hich-pressure (1 cm.) of naphthalene

mercury

arc lama was filtered

12.6 g. in isooctane

2981

1 1.

throuh-h

2982

No.31 Table 1

Photoaddition

Olefin

of Diethyl Oxomalonate Oxetane(m.p.)

to Olefins

Yield %a)

NMR rb)

IR cm?')

Ha,Hb (C6H5)2

-Diphenylethylene

Ha

c' Hb

(co2c2H5)r

4.87s

0

(Co2C2H5b

3 Ha

hb

967

(94-95")

CH a-Methylstyrene

64

4.75d

76

975

5.83d
(59-60°)

Hb'

exo-adduc+ 5.28d

Norbornene

986

(JAB'=:cps) endo-adduct 5.82t 990 (“;lB-JAC =4 cps)

H H

(Co2C2H5b Isoprene

5.30d

90 Ha-k-6 Hb

2,3-Dimethyl-1,3-butal:.ene

5.57d

(JAB=5 cps)

(Liquid)

y+(C02C2H5& H

960

42e)

4.96d

976

6.05d Hb

(JAB=5 CPS) (Liquid)

a> Rased

on consumed diethyl

oxomalonate.

b> The NMR spectra of the oxetanes are generally found to show the hydrogens cx to oxygen

on the rirg at 5.0-6.0~ while hydrogens

g to oxygen

occur at 6.4-

7.473. cl

The infrared

spectre of the oxetanes

that has been assigred involving

show the characteristic

to the asymmetrical

the carbor-oxygen

ring stretching

bonds.

d) These two isomers were separated by chromatographv characterized camphors

e> A

4

.

on silica gel and

b:: the, NMR spectra which were compared

Product ratio of exo-adduct

great proportion

band at 970 cm:'

vibration

with those cc- and &hloro-

to endo-adduct

csf 2,3-dimethyl-1,3-butadiene

was 3 to 1.

had polymerized.

No.31

2983 studied the chemical

and physical

properties

I had weak absorption

bands at 372

mu (E 25) and 367 mu (E 24)

We further oxomalonate

(I).

in n-heptane

and these bands

In addition,

I was photo-reduced Moreover,

cyclohexane.

showed a hypsochromic

I showed phosphorescent

and 527 mw (54.2 kcal./mole) Consequently, kcal./mole

s::ift in more polar solvent.

tartronate

and its pinacol

bands at 530

mp (53.9

in

kcal./nole)

in l,l-difluoro-1,1,2,2-tetrachloroethane.

2,3-dimethyl-1,3-butadiene

whose lowest triplet

in s-cis form and 60 kcal./mole

by energy transfer

in s-trans

of oxetane was 0.30 at 366OA.

data suggest that this reaction

energy is 54

one had largely polymerized

from I to s-cis-2,3-dimethyl-1,3_butadiene.

quantum yield for formation physical

to give diethyl

of diethyl

would proceed

Furthermore,

These chemical

through

the

and

a characteristic

reaction of the carbonyl triplet n,n* excited state 5 . On the other hand, thermal diethyl

(2-phenyl-propen-2-yl)

reaction

tartronate

ethylene did not react with I.

of I with a-methylstyrene

(IV) in 58% yield but l,l-diphenyl-

2,3-Dimethyl-1,3-butadiene

3,4-dimethyl-5,6-dihydro-l,2-pyran-6,6-dicarboxylate From these results, these photochemical

the following

reactions. ,/__\

triplet reaction

electron-defficient

V

ground

by Achmatowicz

to produce the more stable diradical

by Biichi et al. 6 .

to photochemical

through the polarized as reported

of the

oxygen atom of the carbonyl n,n* excited state on the ole finic

(V) as proposed

In contrast

III

of I with olefin would proceed by attack

carbon atom with a high free valency intermediate

(co2c2H5?z

-

bO2C2H5

The photochemical

schemes for

L/

,&02C2Hs

I

and I gave diethyl

in 82% yield.

we would like to propose

and thermal

gave

reactions,

thermal

reactions

may proceed

state of I and so lead to inverse addition

for carbonyl

cyanide ‘/ .

products

No.31

a-Methylstyrene C

6+ b6 5>=CH2

-

H

+

+

+

~_~/C”2’:2H5

-

\02C2H5

CH3

l

C”3

,C-CH2 a- [ co c B O-C' 22 5 co2c2H5

\Co2C2H5 IV

I

Interestingly, the oxetanes obtained here are relatively stable to acid, heat and alkali and accordingly it should be possible to convert them into useful derivatives retaining the trimethylene oxide ring.

References 1. 0. Achmatowicz and 0. Achmatowicz, Jr., Chem. Abstracts, 2, 2. 0. Achmatowicz and A. Zamojski, ibid., & 3.

6333~

8610b (1963).

(1958).

Letters 1425 (1964). D. R. Arnold, R. L. Hinman, and A. H. Glick, Tetrahedron --

4. W. D. Kumler, J. N. Shoolery, and F. V. Brutcher, Jr., J. Amer. Chem. Sot., g, 5.

2533

(1958).

J. Saltiel, R. M. Coates, and W. G. Dauben, ibid., 8,8, 2745

6. G. BGchi, C. G. Inman, and E. S. Lipinsky, ibid., E, 7.

0.

Achmatowicz and M. Leplawy, Chem. Abstracts, 2,

4327

(1966). (1954).

13056a (1960).