Synthesis of Silyl Aziridines and α-Amino Acylsilanes with Silyldibromomethyllithium

Abstract

The reaction of silyldibromomethyllithium with aromatic imines provides r-amino acylsilanes via a bromo aziridine intermediate upon quenching the reaction with water. Alternatively, treatment of the bromo aziridine intermediate with various Grignard reagents or lithium aluminum hydride permits the nucleophilic displacement of the halogen to furnish substituted silyl aziridines.Aziridines are an important class of three-membered Nheterocyclic compounds which serve as versatile intermediates in organic synthesis. 1 Their inherent ring strain activates the carbon-nitrogen bond, and they often serve as good electrophiles. Consequently, aziridine-containing natural products often exhibit strong biological activities because the aziridine motif can act as a powerful alkylating agent for DNA. 2 Recently, Aggarwal et al. have reported that silyl aziridines can serve as useful intermediates for the synthesis of aziridine derivatives. 3 Here we wish to report a novel synthesis of silyl aziridines via a three-component coupling reaction with silyldibromomethyllithium. Additionally, this procedure al-

Lithium Enolates Derived from Pyroglutaminol: Mechanism and Stereoselectivity of an Azaaldol Addition

“…By contrast, mixing enolate 3 with imine 2 15 in neat THF at −78 °C showed promising results, affording β-amino esters 4 and 6 in 10:1 selectivity to the exclusion of other isomers (<0.5%). A number of parameters were examined to optimize the selectivity.…”

Aziridine Synthesis via Nucleophilic Attack of Carbene Equivalents on Imines: the Aza‐Darzens Reaction

“…Racemic zinc reagents undergo reaction with single enantiomers of sulfinimine with excellent stereoselectivity, by means of a closed transition state (Table 6). [32] Thus, trisubstituted aziridines can be obtained by reaction with Grignard reagents, with high trans-stereoselectivity (Table 7). [32] Thus, trisubstituted aziridines can be obtained by reaction with Grignard reagents, with high trans-stereoselectivity (Table 7).…”

“…[30] Table 6. [32] diphenylsulfonium ylides leading predominantly to cisvinylaziridines, and dimethylsulfonium salts lead to transaziridines. [31] More stable ylides, derived from allylsulfonium salts, [35] react in considerably better yields with tosyl- [36] and phosphanyl-imines, and with broader scope, but only if reactions are carried out at very low temperature (typically -100°C) ( Table 8).…”

Metalated Heterocycles in Organic Synthesis: Recent Applications

“…Thus, silyl aziridines can be prepared by reaction of silyldibromomethylithiums with aromatic imines followed by in situ treatment of the bromo aziridine intermediate with Grignard reagents. 297 In addition, 2-phosphono-3-(trimethylsilyl)aziridines have been synthesized by the aziridination of 1-phosphono-2-aza-1,3-dienes with (trimethylsilyl)diazomethane. 298 Epoxysilanes, 299,300 as well as epoxydisilanes 300,301 can be prepared from oxiranylithiums (see Section 2.1.3), although when synthetically useful functionalized silylated epoxides are intended, probably the more convenient route is the epoxidation of vinyl silanes.…”