Titanium-Catalyzed Cyano-Borrowing Reaction for the Direct Amination of Cyanohydrins with Ammonia

Abstract

α-Aminonitrile was an important building block in natural products and key intermedia in organic chemistry. Herein, the direct amination of cyanohydrins with the partner of ammonia to synthesis N-unprotected α-aminonitriles is developed. The reaction proceeds via titanium-catalyzed cyano-borrowing reaction, which features high atom economy and simple operation. A broad range of ketone or aldehyde cyanohydrins was tolerated with ammonia, and the N-unprotected α-aminonitriles were synthesis with moderate to high yields under mild reaction conditions.

Alkynyl Borrowing: Silver-Catalyzed Amination of Secondary Propargylic Alcohols via C(sp3)–C(sp) Bond Cleavage

“…Inspired by the catalytic hydrogen borrowing reactions , and our previous works on cyano borrowing reaction and aryl borrowing reaction, we herein designed the alkynyl borrowing strategy termed transition metal catalytic cleavage of the C­(sp 3 )–C­(sp) bond in propargyl alcohol via β-alkynyl elimination, affording alkynyl-metal and carbonyl species simultaneously. The carbonyl species may undergo condensation with amines to form imines, to which the alkynyl-metal species can be added, affording propargylamines.…”

Copper-catalyzed transfer methylenation via C(sp3)–C(sp3) bond cleavage of alcohols

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In the past decades, transition-metal-catalyzed transformation of alcohols via β-carbon elimination to cleave the unstrained C(sp)-C(sp 3 ) 4, [14][15][16][17] and C(sp 2 )-C(sp 3 ) bonds 4,[18][19][20][21][22] has been widely developed in the field of cross-coupling, 14,19 Michael conjugate addition 17,20,23 and many other reactions. [24][25][26][27] Despite these efforts, transition-metal-catalyzed transformation of unstrained carbon-carbon bond cleavage remains highly desirable but underdeveloped. However, the catalytic cleavage of the unstrained C(sp 3 )-C(sp 3 ) bonds has always been a formidable task and limited success has been met in retro-allylation, [28][29][30] retro-aldol 31 and other reactions.…”

“…Inspired by these previous studies, and our continuous devotion to transition-metal catalyzed β-carbon elimination to cleave the unstrained carbon-carbon bond, [24][25][26][27] we hypothesized to develop a transfer alkylation via transition-metal cata-lyzed cleavage of the unstrained C(sp 3 )-C(sp 3 ) bond of alcohols to access secondary and tertiary alcohols from accessible chemical feedstocks. In the presence of transition-metal catalysts, the C(sp 3 )-C(sp 3 ) bond of alcohols was cleaved via β-carbon elimination, generating an acyl group and a C(sp 3 )metal species, which was then trapped by another active carbonyl compound via carbon-nucleophilic addition, affording the desired products.…”

Rhodium(III)‐Catalyzed Aryl Borrowing Amination of Diaryl Methanols Containing Pyridine‐Directing Groups

“…Despite the success of this transformation, it still suffered from undesired limitations such as the pre-syntheses of imines and the formation of one equivalent of an aldehyde as the byproduct. On the basis of previous investigations into βcarbon elimination, and considering the concept of hydrogen borrowing and our group's work regarding the cyano-borrowing reaction, [15] we designed a new procedure for the amination of alcohols via CÀ C bond cleavage. As shown in Scheme 1e, we hypothesized that the aryl-metallic intermediate (C) and the carbonyl compound (B) could be easily accessed from pyridinedirected diaryl alcohols (A) via Rh(III)-catalyzed β-aryl elimination.…”