-Heteroatom-Substituted 1-Alkenyllithium Reagents: Carbanions and Carbenoids for C–C Bond Formation

Transition Metal Vinylidene- and Allenylidene-Mediated Catalysis in Organic Synthesis

“…59 Vinylidenes can be generated through 1,1-elimination of 1metallo-1-halo-alkenes. 13 It was this α-elimination making use of the acidity of an alkenyl hydrogen that produced the requisite vinylidene intermediate in Taber's total synthesis of (−)-morphine (Scheme 7). 60 afford the cis-fused cyclopentene 19 with exclusive diastereoselectivity.…”

Efficient one‐pot synthesis of 1‐chlorovinyl p‐tolyl sulfoxides from aldehydes and ketones by the Horner‐Wadsworth‐Emmons reaction

“…Much effort has been devoted to developing a synthetic method of alkynes from aldehydes, and Corey‐Fuchs reaction, Seyferth‐Gilbert homologation, and Ohira‐Bestmann modification have been developed. If magnesium alkylidene carbenoids can be directly generated from in situ‐prepared 1‐chlorovinyl p ‐tolyl sulfoxides 1 and a Grignard reagent via the sulfoxide/magnesium exchange reaction, the following FBW rearrangement of the resulting magnesium alkylidene carbenoids is expected to give alkynes (Scheme , Equation 1) [3,4]. We examined the one‐pot conversion of aldehydes into alkynes through the sequential HWE reaction‐sulfoxide/magnesium exchange reaction‐FBW rearrangement (Scheme ).…”

“…The sulfoxide/magnesium exchange reaction of sulfoxides 1 with i ‐PrMgCl generates magnesium alkylidene carbenoids as reactive intermediates, and the resulting magnesium alkylidene carbenoids are converted into various compounds utilizing their diverse reactivity [2]. For instance, the 1,2‐rearrangement of magnesium alkylidene carbenoids, referred to as Fritsch‐Buttenberg‐Wiechell (FBW) rearrangement, leads to the formation of alkynes (Scheme , Equation 1) [3,4]. Sulfoxides 1 also act as Michael acceptors toward nucleophiles.…”

“…In addition, only the synthesis of 2‐monosubstituted sulfoxides 1 from aldehydes has been attempted, and the synthesis of more challenging 2,2‐disubstituted sulfoxides from ketones has not been examined. The development of an efficient synthetic method that permits convenient access to a wide range of sulfoxides 1 is expected to facilitate further advancement of the chemistry using sulfoxides 1 [1-6]. Herein, we report a one‐pot synthesis of 1‐chlorovinyl p ‐tolyl sulfoxides from chloromethyl p ‐tolyl sulfoxide, diethyl chlorophosphate, and carbonyl compounds.…”