The chemistry of photolytically and thermally generated α-ketocarbenes from iodonium ylides of β-diketones

Tetrahedron Letters,Vol.28,No.38,pp Printed in Great Britain

THE CHEMISTRY IODONIUM

OF PHOTOLYTICALLY

4449-4450,1987

AND THERMALLY

0040-4039/87 $3.00 + .oo Pergamon Journals Ltd.

GENERATED

a-KETOCARBENES

FROM

YLIDES OF 8-DIKETONES Lazaros

P. Hadjiarapoglou

Laboratory

of Organic

University

of Thessaloniki,Thessaloniki

Summary:The

Chemistry,Department

reactions

products

of Chemistry,Aristotelian

GR 54006,GREECE

of Phenyliodonium

bonds were investigated.The

192

dimedonate,l,with

are always

various

heterocyclic

double

copmounds(5-member

ring) in good yield. Until today,chemical reactivity

studies

on I-ylide

toward highly electrophilic

When a suspension in the presence

agents3

1 have been limited

and thermal decomposition.

of I-ylide 1 in carbon disulfide

of catalytic

amounts

to its

of Cu(acac)2,in

was heated under reflux

an atmosphere

4-oxo-4,5,6,7-tetrahydro-6,6-dimethyl-l,3-benzoxathiole-Z-thione4

of N2,the ,Z,was isola-

ted in 85% yield. ::

/p _+ IPh

+

Cu(acac)2,

CS2

S

N2

ref IUX

0

il

’

-a

0

0

\\

i

S

-2

1

In the same way,ysing

phenyl

isothiocyanate,the

isolated

product

phenylimino-4-oxo-4,5,6,7-tetrahydro-6,6-dimethyl-l,3-benzoxathiole,3,in

was 274%

yield. Fi

/p 80”. -;Ph

0-

\\

+

C~(acac)~

N2

PhN=C=S -a

’

-3

1

In the reaction presence

,kkP,

0

of Cu(acac)2,in

of I-ylide

1 with acetonitril

an atmosphere

hydro-6,6-dimethyl-1,3-benzoxazol,4,was

of N2,the isolated

in the

in 84% yield.

4

1 When a suspension

under reflux

l-methyl-4-oxo-4,5,6,7-tetra-

of I-ylide 1 in acetonitril

4449

was irradiated(400W

lamp,

4450

low pressure

Hg) in the presence

of an alkene,5,the

2,3,4,5,6,7-hexahydro-benzofuran',6,was

corresponding

Z-phenyl-4-oxo

isolated.

_/,O y

‘\:$h

CHSCN,

i-

hv

PhCH=CHR

/

L

5a,R=H

6a,R=ti

5b,R=PhCH=CH

6b,R=PhCH=Ch,50

In all the above reactions,we irradiation

or thermally

to a diketocarbene responsible results

and PhI.The

for the reaction

obtained

believe

in the presence

spin multiplicity

AND

!.Fellow

ZERVAS"Foundation

Z.Present D-6600

amounts'

of Cti(acac)Z)

of the carbene which

to be triplet 7 in view of

photolysis

REFERENCES of "NAPOLEON

that the I-ylide decomposes(on

of catalytic

has estimated

from the sensitized

95

ii tile

of diazodimedone.

NOTES:

address:Organische

for years

Chenqie,Universitat

1985 and 1986.

des Saarlandes,Fachbereichl4.1,

Saarbrucken,W.Germany.

3.Koser

F.G., "The Chemistry

1983,Supplement

D,Chapter

4.Papadopoylou The authors

believe

S.:Varvoglis

A.,J.Org.Chem.,1985,50,15lD.

that they have prepared

the dimer,7,which

after the elimination

York

18,pp 774-806.

M.;Spiroudis

they prepared

groups" ,Wiley-Interscience,New

of Functional

the thione

2.The correct

comes from the dimeriration

is that

of the species

of Phi.

/P

Yq L’

iPh

+

CS2

rt -------

\\ 0

Using their procedure,the for the methylenes with the proposed methylenes masked

of dimedone structure

of dimedone

product

in

1

H NMR(DMSO-d6)has

ring in the region of 2,406.This

7.The thione 2 has two singlets

ring with 23 Hz difference,which

a singlet is in agreement

for the two

is difficult

to be

by the solvent.

5.Yoshida

J.;Yano

S.;Ozawa

6.The amount of Cu(acac)* 7.Hayasi

Y.;Okada

Aknowledgement:I _------- ____support

isolated

during

(Received

T.;Kawabata

is 20mg per mmole of I-,ylide 1.

T.;Kawanisi

M.,Bull.Chem.Soc.Jpn.,l970,43,2506.

thank the "Napoleon the preparation

in UK 22 July

N.,J.Org.Chem.,1985,50,3467.

Zervas

of this work.

1987)

Foundation"for

their financial