Atom-Economical Thiocyanation-Amination of Alkynes with N-Thiocyanato-Dibenzenesulfonimide

Abstract

A highly regioselective protocol for intermolecular thiocyanation-amination of alkynes by N-thiocyanodibenzenesulfonimide (NTSI) as the SCN and nitrogen sources has been developed. A C−S bond and C−N bond are simultaneously constructed in only one step. The reaction under simple mild conditions features a broad substrate scope, atom economy, high yields (up to 94%), and excellent functional group tolerance.

Dithiocyanation of Alkynes with N‐Thiocyanato‐dibenzenesulfonimide and Ammonium Thiocyanate

“…It is worth noting that some substrates containing powerful electron-donating group (2 d) gave more thiocyanation-amination by-product under the optimal reaction conditions, which could be inhibited by addition of aqueous hydrochloric acid resulting from the formation of the neutral dibenzenesulfonimide with reduced nucleophilicity. [10] Meanwhile, ortho-substituted (2 k) and meta-substituted alkynes (2 l-2 n) were also applicable to this method and converted to 1,2dithiocyanated alkenes in high yields. Symmetric diarylacetylenes (2 o, 2 p) could be transformed to the corresponding products smoothly.…”

“…As shown in Scheme 2, a series of 4‐( p ‐tolylethynyl)benzene derivatives bearing electron‐withdrawing (F, Cl, Br, CO 2 Et, NO 2 , CF 3 , CN) and electron‐donating (Me and OMe) groups at the para position of benzene ring produced the corresponding products ( 2 a – 2 j ) in good to excellent yields. It is worth noting that some substrates containing powerful electron‐donating group ( 2 d ) gave more thiocyanation‐amination by‐product under the optimal reaction conditions, which could be inhibited by addition of aqueous hydrochloric acid resulting from the formation of the neutral dibenzenesulfonimide with reduced nucleophilicity [10] . Meanwhile, ortho ‐substituted ( 2 k ) and meta ‐substituted alkynes ( 2 l – 2 n ) were also applicable to this method and converted to 1,2‐dithiocyanated alkenes in high yields.…”

“…[9] In 2021, we reported a regioselective thiocyanation-amination of alkynes by Nthiocyanato-dibenzenesulfonimide (NTSI). [10] It prompted us to envision the possibility of developing a general method for vinyl dithiocyanates from alkynes with cationic SCN + and anionic SCN À sources (Scheme 1d).…”

“…Our group have developed some electrophilic thiocyanating reagents to perform direct electrophilic thiocyanation reactions, [8] especially asymmetric thiocyanation reactions over the past few years [9] . In 2021, we reported a regioselective thiocyanation‐amination of alkynes by N ‐thiocyanato‐dibenzenesulfonimide (NTSI) [10] . It prompted us to envision the possibility of developing a general method for vinyl dithiocyanates from alkynes with cationic SCN + and anionic SCN − sources (Scheme 1d).…”

Recent advances in photochemical and electrochemically induced thiocyanation: a greener approach for SCN-containing compound formation

“…1A) catalyzed by transition metals or nonmetals through a traditional technique or with the use of stoichiometric oxidants. 4,5 As a result, a number of well-established and highly successful methods for generating C–SCN bonds have been developed and are already well-reviewed, which is critical to the advancement of organic thiocyanate research. 1 e…”