Enantioselective Synthesis of α‐Aminosilanes by Copper‐Catalyzed Hydroamination of Vinylsilanes

Abstract

The synthesis of α-aminosilanes by a highly enantio-and regioselective copper-catalyzed hydroamination of vinylsilanes is reported. The system employs Cu-DTBM-SEG-PHOS as the catalyst, diethoxymethylsilane as the stoichiometric reductant, and O-benzoylhydroxylamines as the electrophilic nitrogen source. This hydroamination reaction is compatible with differentially substituted vinylsilanes, thus providing access to amino acid mimics and other valuable chiral organosilicon compounds.

A Modified System for the Synthesis of Enantioenriched N‐Arylamines through Copper‐Catalyzed Hydroamination

“…In light of our previous studies, [9] we began our investigation by exploring the reactivity of N- arylhydroxylamine esters using styrene as the model substrate, ( S )-DTBM-SEGPHOS/Cu(OAc) 2 as the precatalyst and (MeO) 2 MeSiH [10] as the stoichiometric reductant. We chose to employ the 4-diethylaminobenzoate ester of phenylbenzylhydroxylamine ( 2a ) as the electrophilic amine source.…”

“…In the case of aliphatic amines, reagents bearing this modified leaving group were found to possess better stability and enhanced reactivity relative to the benzoate esters (Scheme 1a). [9e,f] Under these conditions, a small amount of the desired product 3a (17%) was formed in a moderately enantioselective manner (41% ee ) (Scheme 1a). A significant amount of N- benzylaniline was also formed by reductive cleavage of the N–O bond of 2a (Scheme 1b).…”

“…Both cis- and trans-β -substituted olefins yielded the corresponding products in similar yields and in a stereoselective manner as we previously reported. [9a] Moreover, the reaction with 3-vinylpyridine provided 3g in an efficient manner. The catalyst system also achieved high levels of diastereoselectivity in the hydroamination of ( R )-limonene ( 3i, 3i′ ).…”

Synthesis of β‐Boryl‐α‐Aminosilanes by Copper‐Catalyzed Aminoboration of Vinylsilanes

“…[2] Them ost studied strategy for the preparation of the a-aminosilane relies on the nucleophilic silyl addition reaction:the highly diastereoselective addition of silyllithium to sulfinyl aldimines; [2c,d,3] the copper-catalyzed enantioselective addition of the silylborane to sulfonyl aldimines. [4] On the other hand, Buchwald [5] recently reported acopper-catalyzed enantioselective hydroamination of vinylsilanes with hydroxylamines as electrophilic amination reagents. [6] This approach is based on the nitrogen addition across alkenes and ag ood alternative to the above silyl addition protocols.D espite the above certain advances,there still remains alarge demand for further development of catalysis directed toward versatile and highly functionalized a-aminosilanes.…”

Copper(I)‐Catalyzed Interrupted Click Reaction: Synthesis of Diverse 5‐Hetero‐Functionalized Triazoles

“…Almost no thioalkyne (6) was observed in the reaction. Theh ighest isolated yield (90 %; Entry 10) was obtained by raising the temperature to 40 8 8C and increasing the amount of 3a to two equivalents.Using an electrophilic amination reagent (9a), [15] 5-amino triazole (10 a)c ould be obtained in 83 %y ield by as imilar CuIcatalyzed three-component reaction [Eq. Thee xpected thiotriazole was not observed, but only the click product (5a;E ntries 2a nd 3).…”