Reaction of sulfur dioxide with enol ethers - American Chemical Society


[(C6H5S)2C]2CuLi + ... c c6h5. H. H ch3. 94 d. CsHb ch3 ch3 ch3. 82 e. C6Hr,. CsHa. H ch3. 94 .... product III (eq 2); and (c) the elimination of the ...
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8642 room temperature. The resulting precipitate was filtered off and after T H F was evaporated under reduced pressure, the organic layer was extracted with ether. The extract was dried with Na2S04 and concentrated. Separation by silica gel column chromatography from impurities gives IIIc, homogeneous by tlc and having ir and pmr spectra and elemental analysis in accord with the assigned structure [pmr T 2.49-3.03 (m, 15 H), 7.28 (m, 2 H), 7.66 (m, 2 H), 8.06 (s, 3 H)]. The generality of the reaction between copper reagents of thioacetal (I) and conjugated enone is apparent from the results summarized in Scheme I and Table I. Scheme I

R'

R2

1

+

[(CGHjS)2C]2C~Li

0

\

R3/

II

C==CH-C-R4

-+

I1

I

Ri R2

'

I (CsH&C-C-CHZC-R I

7

OH

I ' + R4-C-CH=C ~\

I

R3

R3

R'-C(SCsH&

111

IV

Table I I R'

7 -

II------

R2

R3

R4

H H H CH3

H H H CH, H H H H

CHI CH 3 CH3 CH3 CH3 CGH; CH 1 CH,

CP,

CsHj H

h

IIIC-f

2CuCl

23

C&I CH( SC,H

I -n BuI 1 cur I ( H CCH =c H

)?

/I

0

I/

n-C,H ,C SC,H ),CH2CH-CCH

4

.

VI1

0 IZ

(4) T. Mukaiyama, I