Silver‐Catalyzed Stereoselective Aminosulfonylation of Alkynes

Abstract

A silver‐catalyzed intermolecular aminosulfonylation of terminal alkynes with sodium sulfinates and TMSN3 is reported. This three‐component reaction proceeds through sequential hydroazidation of the terminal alkyne and addition of a sulfonyl radical to the resultant vinyl azide. The method enables the stereoselective synthesis of a wide range of β‐sulfonyl enamines without electron‐withdrawing groups on the nitrogen atom. These enamines are found to be suitable for a variety of further transformations.

The hydrogen atom transfer reactivity of sulfinic acids

“… 61 If the reaction were this fast in organic solvent, reactions involving sulfonyl radicals would be impossible under aerobic conditions. 12 , 13 , 17 For example, under the reaction conditions developed by the Lei group for oxidative functionalization of alkynes, 13 both the addition of sulfonyl radicals and the addition of oxygen would have effective rates of around 1 × 10 7 s –1 . Therefore, yields of 80% would be impossible, since the sulfinic acid (present in excess) would simply autoxidize.…”

Oxidative Sulfonylation of Multiple Carbon‐Carbon bonds with Sulfonyl Hydrazides, Sulfinic Acids and their Salts

“…Such β-sulfonyl enamines are useful intermediates for the synthesis of β-ketosulfones, 2Hazirines, dihydropyrroles, and imines (Scheme 79). [98] β-Sulfonyl enamines were also synthesized via sulfonylation of vinyl azides with sodium p-toluenesulfinate or sulfonyl hydrazides under the action of AgNO 3 [99] or electric current respectively. [100] One-pot synthesis of β-phenoxyvinyl sulfones through the reaction between alkynes, sodium sulfinates, and phenols was performed under the action of I 2 /K 2 CO 3 in EtOH at 60°C.…”

Recent Advances in Silver‐Catalyzed Transformations of Electronically Unbiased Alkenes and Alkynes

“…In 2017, Bi et al firstly disclosed a silver-catalyzed synthesis of various functionalized enamines from terminal alkynes, trimethylsilyl azide and sodium sulfinates under mild conditions, rendering a wide variety of aminosulfonylated products with good functional group tolerability and high stereoselectivity (Scheme 18). [32] The ingenious combination of vinyl azide with sulfonyl radical in this reaction was suggested to avoid the formation of unstable vinyl radical intermediate and thus inhibited many possible side reactions. Mechanistic study of in-situ NMR experiments clearly presented the changes of terminal alkynes, vinyl azide and the desired product during the whole process, providing more insight to the reaction pathway.…”