The phenyl-isocyanide reaction with diborane

Tetrahedron Letters No.52, Printed in Great Britain,

PP. 4775-4778,

THE PHENYL-ISOCYANIDE Sihano

Bresadola,

Sock&a*

REACTION

Francesco

Edison

1965.

Chimica,

Istituto di Chimica Generale,

Ltd.

WITH DIBORANE

Rossetto

- Aaienda

Pergamon Press

and Giorgio Bollate,

Unirersita’

Puosi

hiilanq

di Padora,

Italy. (Received We have previously

1 November 1965)

reported

the preparation

compound I which was obtained by reaction boron (1). This compound is structurally II reported

by Hesse

I

analogous

to the phenyl derivative

I

)2

(C,Hs )zB

/C-b%

8, 2

of the

with triethyl-

and Witte (2).

C,H,--dlik-(C,H, (C,H, 1zB,

and characterisation

of ethylisocyanide

C-C,H5

2,I CsH,

5

II

I

In view of the existence

of these two compounds,

investigations

hare been now

extended to the reaction

products

with diborane.

Contrary

the observation

of Casanova

of isocyanides

(3) we reported

4775

(1) that the reaction

to

of isocyanides

With bile Indeed,

can be carried

out without great difficulty

the extreme versatility

of these reactions

owing the diWiculty in the separation progress

on the reactions

makes complicate

of the reaction

of some aliphatic

under controlled

products.

and aromatic

conditions. this study

Work

is

isocyanides

in

with

diborane. Recently,

J.Tanaka

In this comanication the existence

has reported

we report

(4) the preparation

part of the results

LLnew type of ring IV,

isomeric

III

The procedure

of investigations

III.

concerning

with III.

I'd

followed

from that of Tanaka reproducible

of the derivative

results.

in the preparation

(4) leading to III. However,

of IV is different

in some details

The method of preparation

following

Tanaka’ s procedure,

of IV gives we were

unable

to obtain III as a pure compound. Compound IV can be prepared the following

to a 5% solution

of phenylisocyanide

_SOeC) with rigorous a+68eC.

reacting

method. A stoichiometric

stirring

phenylisocyanide

amount of diborane

in anhydrous

and the temperature

A white solid cristalline

with diborane was slowly

with

added

petroleum ether (b.p.:

30-

of the mixture was maintained

product was immediately formed.

The mixture

No.52

4777

after addition of the diborane always

at the temperature

Filtration

under nitrogen

sensitive

and soluble

poses in alcohols,

ketons,

indicates

N, 12,25$.

CHCl,

pyridine,

decomposing

Vapor

Pressure

in the 1650-2250 and rules

The same result

calculated

range.

out the possibility

A

*e infrared

While the former

assignement

is confirmed

the in-plane

deformation

deformation

w 234).

C groups

are not present,

spectrum

shows in addition

two bands of strong absorption

to a -C=N-

to -BHs groups.

bands at 1140 cml,

mode, and by that at 968 cm-,

mode, of the BHs groups solutions,

(5).

typical

intensity

1140 and

stretching

We assign

mode of BHs groups.

by the absorption

The bands

Is a simple coordinative

strong band is assigned

(5% CHaCla and 5s CDClr

is twice

hare no absorption

and 2360 cm1 and bands of medium intensity at 2260,

2360 and 2260 cm? to the B-H stretching

spectra

hydrogens

weight (hfechrolab

for (C&NCBH,)r

that this substance

mode, the other bands can t-s assigned

-plane

two hidrydic

hare been obtained by acid

This shows that -NE

to bands expected for a phenyl group,

968 cm-.

elementary

Typs 301 A) found at 25% is 232. This value

compound of the type RNC --+

at 1589 cm’

decom-

Found B, 9,OO$;

The molecular

in nujol and hexachlorobutadiene cm-

air

and has not a sharp

weight of the compound under investigation

the value of the 1:l adduct (M.W. spectra

product,

B, 9.2346; N, 11,98$.

by Tanaka (4).

Osmometer

shows that the molecular

infrared

dimethylsulfoxide

at 135’C. Quantitative

BHr requires:

as suggested

Hence, in vacuum.

The compound slowly

of the product with methyl alcohol

for boron atom hare been found. hydrolysis,

and CHIC&.

that this compound is a 1:l adduct.

CaHsNC -

By solrolysis

to stir for three hours.

the mixture was concentrated

gave a homogeneus white cristalline

in CaH‘,

melting point but starts analysis

was allowed

of -68’C,

the band at

This typical of of the out- of-

Also the proton resonance

37@C, Varian

A 60) hare been

4778

No.52

recorded

at 60 MC relative

to tetramethylsilane

as internal

of the poor ~.olubility of the product under investigation, is not possible

to obtain good resolution

which to identify separately the -CH=N-

groups.

However,

that aliphati 3 -CHa groups are found in the 1,5-t,5 Hence,

compound with structure molecular

from the N.M.R.

range,

of structure

existing

of -CHa aliphatic

as analytical,

it

from of

to conclude

In fact,

no signals

groups.

above reported

the

spectroscopic

and

carbon,

nitrogen

and 4-coordinated

Acknowledgments.

The authors

and stimulating

suggestions

between compounds I, II and IV clearly

of the same type of heterocyclic

helpful

no Cavalli

range

data it is possible

the procedure

IV is obtained,

that they are all members

containing

p.p.m.

protons and protons

in this molecule.

typical

that following

At cause

data show.

The analogy shows

of aromatic

are not present

p.p.m.

one can conclude

in the 6,5-7,5

the signals

standard.

from these spectra

wish to thank Professor discussions

for the proton NMR spectral

ring

boron atoms. AIdo Turco

for

and are indebted to Dr.

Luci_a

work.

REFERENCES 1) S.Bresadola,

G.Carraro,

C.Pecile

and A.Turco,

Tetrahedron

Letters,

3185 (1964). 2) G.Hessa

and H .Witte,

5) J.Casanova, 4) J.Tanaka 5) A.D.Cross, London,

Jr.

Ang.Chem.,

and R.E.Schuster,

and J.C.Carter, Introduction (1960).

3,

791(1963). Tetrahedron

Tetrahedron to or actical

9 -

Letters,i,

405 (1964).

Letters ,r, 329 (1965). I.R.Spectroscopy, Butterworths,