New syntheses of 1- and 2-phenylthiobutadienes

Abstract

The Horner-Wittig reaction with sulphenylated allylphosphine oxides and the rearrangement and oxidation of a-hydroxy-bis(pheny1thio) acetals are used to make 1-and 2-phenylthiobutadienes respectively. DIELS-ALDER reactions with l-phenylthio (1-PhS) butadiene give cyclic ally1 sulphides (e.g., 1) from which allylic alcohols, cyclic dienes, or aromatic compounds can be made.l 2-PhS butadiene on the other hand gives cyclic vinyl sulphides (e.g., 2) which are potential ketones.2 Both these reactions ( 1 )(2)

Synthesis of E- and Z-vinyl ethers by the Horner–Wittig reaction

“…The heptaldehyde adduct (20; R1 = H, R2 = n-C,H13) was separated into pure alcohol (27; R2 = n-C,H,,, R3 = H) and a 1 : 2 mixture of ( 27) and ( 29) (R2 = n-C,H,,, R3 = H) by fractional crystallisation from ethyl acetate. The original mixtures contained (27) and (29) in 6 : 5 arid We have previously reported 279 28 similar reactions with a-(phenylt hio) -and a-(methylthio) -alkylphosphine oxides (31; R2 = Ph, Me). These form anions easily, but addition to aldehydes or ketones then gives the vinyl sulphides (33) directly.…”

“…The methoxymethyl compound (18) added equally well to aldehydes or ketones giving mixtures of diastereoisomers of (20). The anisaldehyde adduct (20; R1 = H , R2 = $-MeOC,H,) was separated into the two pure crystalline alcohols (27) and (29) (R2 = $-hfeOC,H,, R3 = H) by column chromatography. The heptaldehyde adduct (20; R1 = H, R2 = n-C,H13) was separated into pure alcohol (27; R2 = n-C,H,,, R3 = H) and a 1 : 2 mixture of ( 27) and ( 29) (R2 = n-C,H,,, R3 = H) by fractional crystallisation from ethyl acetate.…”

“…This, we believe, is another consequence of the possible destabilisation of carbanions by oxygen atoms in contrast to the stabilisation by sulphur. 27 The reaction (18) to (21) can be carried out in one step by working at a higher temperature (room temperature or above) but yields are usually poorer. Schlosser 23 reports one example of this reaction (same compounds as Entry 8, Table 1) in 35% yield.…”

“…spectra of the corresponding sulphur compounds (32) and enabled us to assign configurations to these alcohols and to the vinyl sulphides derived from them.28 In addition, the reaction to give the vinyl sulphides ( 33) can be carried out in one step and is then normally stereoselective in favour of the Eisomer. 27 The n.m.r. spectra of these vinyl sulphides also conformed to the pattern established for the vinyl ethers.28…”

“…The hydrolysis of vinyl sulphides to ketones, though needing more vigorous conditions than the hydrolysis of vinyl ethers, can be carried out quite easily. 27 The aldehyde synthesis ( 18) to ( 21) is an alkylative transposition on the original carbonyl compound (42) and a synthesis with umpolung,16 as the reagent ( 19) is a formyl anion (-CHO) equivalent.…”