A Stereocontrolled 1,2‐Addition Reaction of Tetrazoles with Alkyl Propiolates for the Synthesis of Highly Functionalized Enamines

Abstract

A stereocontrolled 1,2-addition reaction of 1-aryl-1H-tetrazoles with alkyl propiolates for the synthesis of highly functionalized enamines was developed. In the presence of silver oxide (Ag 2 O), the 1,2-addition reaction generated (Z)-N-cyano enamines in good yields with exclusive formation of the Z-isomers. Meanwhile, the 1,2-addition reaction gen-erated (E)-N-cyano enamines in the presence of Ag 2 O and potassium carbonate (K 2 CO 3 ) with high stereoselectivity and yields.

Late Transition Metal-Catalyzed Hydroamination and Hydroamidation

“…512 The Z-and E-N-cyano enamines can be selectively obtained in good yields in the absence or presence of K 2 CO 3 via a silvermediated 1,2-addition of aryltetrazoles with alkyl propiolates (Scheme 122). 513 A subsequent allenoate isomerization of the Z-to the E-isomer can be performed using 2 equiv of K 2 CO 3 . alkenyl-, and alkyl-substituted iminoalkynes (Scheme 123).…”

Silver-catalysed reactions of alkynes: recent advances

“…131 Notably, the easy interchange between Z and E isomers can be simply regulated by K 2 CO 3 . 1-Aryl-1H-tetrazoles 149 were recently employed by Zhang and Wang et al as the amino source in the silver-catalysed hydroamination of alkyl propiolates, enabling the stereoselective synthesis of N-cyanoenamines 150 and 151 (Scheme 59).…”

“…1-Aryl-1H-tetrazoles 149 were recently employed by Zhang and Wang et al as the amino source in the silver-catalysed hydroamination of alkyl propiolates, enabling the stereoselective synthesis of N-cyanoenamines 150 and 151 (Scheme 59). 131 Notably, the easy interchange between Z and E isomers can be simply regulated by K 2 CO 3 . This is the first example of the application of tetrazole as a potential synthetic equivalent of cyanamide.…”

Copper-Catalyzed Alkenylation of Cyanamides

“…If they clearly hold promises as functional groups for the design of new transformations, they can, however, be hardly prepared to date. Indeed, most methods available for the synthesis of other classes of cyanamides cannot be extended to the preparation of N -alkenylcyanamides, and only push–pull or N -vinyl derivatives can be prepared by condensation of cyanamides with β-keto esters or tetrazoles with propiolates and by the von Braun reaction from piperazines, respectively.…”