Helical Chiral 2,2′-Bipyridine N- Monoxides as Catalysts in the Enantioselective Propargylation of Aldehydes with Allenyltrichlorosilane

Abstract

A highly enantioselective synthesis of homopropargylic alcohols is achieved by using the new helical chiral 2,2'-bipyridine N-monoxide catalyst and allenyltrichlorosilane. This method can be further extended to the enantio- and regioselective propargylation of N-acylhydrazones.

Helicene-Based Chiral Auxiliaries and Chirogenesis

“…Similarly, enantiopure helical 2,2 -bipyridine-N-monoxide 99 was prepared in two steps from enantiopure 93 with 95% yield (Scheme 17a) and applied as a Lewis base type catalyst for the highly enantioselective reaction between aldehyde, 100, and allenyltrichlorosilane 101 to obtain enantiomerically enriched homopropargylic alcohol 102 [68]. The reaction displayed high conversion (78-97%) and 74-96% ee for various ortho-and para-substituted aromatic aldehyde derivatives, with 18 examples in total (Scheme 17b).…”

2.05 Propargyl and Allenyl Organometallics

“…Takenaka and coworkers were also interested in the applications of allenyltrichlorosilane. 41 Before their work, only one moderately enantioselective use of this reagent in asymmetric catalysis was reported. The helically chiral Lewis base catalyst 109 appeared to be a highly enantioselective and efficient mediator of asymmetric propargylation (Scheme 23, Table 37).…”

Synthesis, Structure, Fluorescence, and Theoretical Studies of CuCl(2,2′-Bipyridine)2·3.5H2O

“…Metal halide-2,2 0 -bipyridine compounds have attracted increased attention in recent years not only for their intrinsic aesthetic appeals, but also for their various potential applications, such as catalysis, biochemistry, photochemistry, sensitizers in solar energy conversion, electrical conductivity, nonlinear optical behavior, ion exchange, and so forth. [1][2][3][4][5] We focus here on metal halide-2,2 0 -bipyridine compounds, which may possess novel structural motifs and properties. We report herein the preparation, X-ray single-crystal structure, and photoluminescence of CuCl(2,2 0 -bipyridine) 2 ¢3.5H 2 O (1), which was synthesized from a hydrothermal reaction.…”