Enantioselective Synthesis of α,α-Difluoro-β-amino Acid and 3,3-Difluoroazetidin-2-one via the Reformatsky-Type Reaction of Ethyl Bromodifluoroacetate with Chiral 1,3-Oxazolidines

Abstract

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Enantioselective acylation of alcohols with fluorinated β-phenyl-β-lactams in the presence of Burkholderia cepacia lipase

“…3,17 Compound (S)-6 was previously prepared, based on various Reformatsky-type reactions in the presence of chiral auxiliaries. 18,19 On the other hand, the key step to (2S,3S)-7 was the tandem conjugate addition of lithium (S)-N-benzyl-N-a-methylbenzylamide to tert-butyl cinnamate. 20 Based on these articles, the absolute configurations of the present resolution products are known (see Section 4.5) and are shown in Scheme 1.…”

“…20 Based on these articles, the absolute configurations of the present resolution products are known (see Section 4.5) and are shown in Scheme 1. The main benefit of the lipase-catalyzed kinetic resolution pathways over the published synthetic routes to enantiopure compounds 18 is that chiral induction now is catalytic rather than stoichiometric, meaning there is no need to prepare enantiopure auxiliaries, and mild reaction conditions are possible.…”

One-pot synthesis of 4,4-difluoro-3-oxo-2-(triphenylphosphoranylidene)-δ-lactones by Reformatsky reaction

“…It was reported that the Reformatsky reactions of halodifluoroacetate with aldimines and chiral 1,3-oxazolidines usually gave difluorinated b-lactams [18][19][20][21]. However, the similar reactions of 4-bromo-4,4-difluoroacetoacetate with aldimines and ketimines were reported to give complicated results [22].…”

SmI2-promoted imino-Reformatsky reaction for facile synthesis of enantioenriched β-amino acid esters

“…Of the methods developed, asymmetric addition of Reformatsky-type reagents to imines is known as an attractive strategy for optically active -amino acid esters preparation. In recent years, a number of different chiral auxiliaries [8][9][10][11][12][13] as well as catalysts [14] has been introduced to provide the products with high stereoselectivities. Among them, the chiral sulfoxides are found as one of the best auxiliaries for the advantages of good stereodirecting and facile removal [15][16][17][18][19].…”