Reaction of Silyldihalomethyllithiums with Nitriles:  Formation of α-Keto Acylsilanes via Azirines and 1,3-Rearrangement of Silyl Group from C to N

Abstract

A synthesis of alpha-keto acylsilanes, where 2-bromo-2H-azirine participates as a key intermediate, is reported. The reaction of silyldibromomethyllithium with aryl nitriles provides alpha-keto acylsilanes in good yields. Interestingly, silyldichloromethyllithium induces aza-1,3-Brook rearrangement of the silyl group in th reaction with nitriles. The rearrangement enables a three-component coupling reaction in a one-pot operation.

Synthesis of various functionalized 2H‐azirines: An updated library

“…Deprotonation of dibromomethylsilane with lithium diisopropylamide (LDA) in THF at −78°C gives tertbutyldimethylsilyldibromomethyllithium, it is added to benzonitrile and then treated with Grignard reagent to produce azirines. The interactions of the intermediate bromoazirine with phenyl‐ and butyl‐magnesium bromide produce direct halide substitution, while aziridine derivative is observed when allyl magnesium bromide reacts to the C═N double bond via a nucleophilic addition (Scheme 102) [124].…”

Durch sichtbares Licht vermittelte Cycloadditionen von α‐Ketoacylsilanen mit Iminen: Einfache Synthese von β‐Lactamen

“…Mit unserem anhaltenden Interesse an der Acylsilanchemie [5h] haben wir unsere Aufmerksamkeit auf a-Ketoacylsilane gerichtet, die eine selten erforschte Verbindungsklasse darstellen. [14] Neben der [1,2]-Silyl-Migration von Acylsilanen zur Bildung von Siloxycarbenen hatten wir die Idee, dass a-Ketoacylsilane theoretisch eine [1,3]-Silyl-Migration zur Bildung von Keten-Zwischenprodukten unterlaufen kçnnten. In dieser Arbeit berichten wir über eine milde, durch sichtbares Licht induzierte Methode zur Erzeugung von Ketenen aus a-Ketoacylsilanen ohne Verwendung von stçchiometrischen Basen oder Metallen, und deren Cycloaddition mit Iminen (Schema 1 b).…”

Stereoselective Synthesis of Enantioenriched 2-Chloro-2-aroylaziridines by Cascade Reaction between Aryl Nitriles, Silyldichloromethanes, and tert-Butanesulfinylimines

“…The anions can subsequently be intercepted by alkyl halides, benzoyl chloride, or benzaldehyde, allowing construction of functionalized α,α-dichloroketones after acid hydrolysis of the N-silyl imine groups. 13 During our studies on Brook rearrangement reactions and their applications for the synthesis of nitrogen-containing compounds, 14 we speculated that the functionalized dichlorocarbanion intermediates generated from Oshima's protocol might serve as nucleophiles in an aza-Darzens-type transformation, resulting in an efficient pathway to access functionalized 2-chloroaziridines (Scheme 1, 5 or 6 → 8 or 8′). Here, we present our study on this cascade reaction, which involves the coupling of aryl nitriles, silyldichloromethanes, and tert-butanesulfinylimines.…”

“…Pioneering work by Oshima and co-workers showed that the reaction of lithium silyldichloromethane and aryl nitriles involves a nucleophilic addition/[1,3]-aza-Brook rearrangement cascade, affording dichlorocarbanions bearing an α- N -silyl imine (or their 1-azaenolate equivalents, Scheme , 1 → 5 or 6 ). The anions can subsequently be intercepted by alkyl halides, benzoyl chloride, or benzaldehyde, allowing construction of functionalized α,α-dichloroketones after acid hydrolysis of the N -silyl imine groups . During our studies on Brook rearrangement reactions and their applications for the synthesis of nitrogen-containing compounds, we speculated that the functionalized dichlorocarbanion intermediates generated from Oshima’s protocol might serve as nucleophiles in an aza-Darzens-type transformation, resulting in an efficient pathway to access functionalized 2-chloroaziridines (Scheme , 5 or 6 → 8 or 8 ′).…”