Chemistry of Ylides. XIX. .beta.-Carbonyl sulfonium ylides

The Synthesis and Reactions of Chiral Sulfonium Ylids

“…The treatments of the achiral analog of (-)-I, dimethylsulfonium phenacylid, 2, with acylating and alkylating agents have afforded various sulfonium compounds as depicted in Scheme 1 (19)(20)(21). The synthesis of (-)-5 and (-)-6 from (-)-I illustrates one solution to the problem associated with racemization of starting material.…”

“…54 h at 25" in CH,CI, (10). Benzoylation of 2 with equimolar benzoic anhydride is reported to require a reaction time of 43 h (21). Even if (-)-5 were t o racemize at the same rate as (-)-I, it would have been impossible to isolate (-)-5 in the reaction time reported.…”

Transition-Metal-Catalyzed Carbenoid Reactions of Sulfonium Ylides

“…4 ]. Dimethylsulfonium (ethoxycarbonyl)methylide (3b) was prepared by reaction of ethyl bromoacetate with dimethyl sulfide (1b), as described by Johnson and Amel for the corresponding methyl ester [14]. The resulting sulfonium salt 2b was deprotonated with NaH to yield 3b.…”

Stereoselective one-pot synthesis of β-alkylsulfide enol esters. Base-triggered rearrangement under mild conditions

“…1 H NMR (400. 16 (Z)-2-(Methylthio)-1-phenylvinyl benzoate (12) 41 The typical above described procedure was followed using first thiobenzoic acid (51.4 μL, 0.44 mmol) with K 2 CO 3 (60.7 mg, 0.44 mmol) in order to in situ deprotonate it, then phenacyl bromide (2, 87.3 mg, 0.44 mmol), methyl iodide (50.4 μL, 0.88 mmol) and K 2 CO 3 (121.4 mg, 0.88 mmol) were added. After extraction, the crude residue was passed through a silica gel pad (eluting with petroleum ether-dichloromethane = 50 : 50) to afford pure 12 as a brownish oil (62.4 mg, 78%).…”