One-pot, cis-selective synthesis of α-substituted β-trimethylsilyl-α,β-epoxyesters from α-ketoesters and diazo(trimethylsilyl)methyl magnesium bromide

An Efficient Synthesis of 2-Diazo-2-(trimethylsilyl)ethanols and Their Application to Pyrazole Synthesis

“…Recently, we reported the one-pot synthesis of cis-b-trimethylsilyl-a,b-epoxy esters from a-keto esters using the magnesium bromide salt of TMSCHN 2 [TMSC(Mg-Br)N 2 ]. 9 In this study, we found that the reaction of TMSC(MgBr)N 2 with ethyl 4-phenyl-2-oxobutanoate at -78°C efficiently gave the corresponding trimethylsilylated diazoalcohol in high yield as an isolable product while the reaction with TMSC(Li)N 2 gave a complex mixture (Scheme 2). From these results, we envisaged that TMSC(MgBr)N 2 would also react with simple aldehydes and ketones to give the corresponding 2-diazo-2-(trimethylsilyl)ethanols.…”

Substituted Pyrazoles and Their Heteroannulated Analogs—Recent Syntheses and Biological Activities

“…In 2006, Hari et al [ 74 ] synthesized di- and trisubstituted pyrazoles 89 by the reaction of (diazomethyl)trimethylsilane ( 86 ) with MgBr 2 and ketones to give 87 , which subsequently reacted with ethyl propiolate ( 88 ) or dimethyl acetylenedicarboxylate ( 42 ) under reflux of THF to give pyrazoles 89 ( Scheme 38 ) [ 74 ].…”

Chemistry of α-Oxoesters: A Powerful Tool for the Synthesis of Heterocycles

“…The preparation of β-trimethylsilyl-α,β-epoxyesters 640 was reported by Hari et al through reaction of α-oxoesters with diazo­(trimethylsilyl)­methyl magnesium bromide (1.2 equiv), followed by treatment with pivalic acid (5 equiv). Reactions were carried out in THF at −78 °C.…”