An Efficient Synthetic Method of 4-Penteneselenoamides: Four-Component Coupling Reaction of Terminal Acetylenes, Selenium, Amines, and Allylic Bromides

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Abstract
The reaction of lithium alkyneselenolates generated from terminal acetylenes, butyllithium, and selenium with amines and allylic bromides proceeded smoothly in THF at 67 °C to give 4-penteneselenoamides in moderate to high yields. The reaction may proceed via selenoketene intermediates bearing an allylic group, followed by the attack of amines to give the products. Aliphatic and aromatic acetylenes, silylacetylene, and enynes were employed as terminal acetylenes. One molar amount of secondary amines was effective, whereas an excess of primary amines was necessary. The reactions with 2-butenyl bromide exhibited high regioselectivity, although they gave the stereoisomeric mixtures. The reactions of silyl ethers of propargylic alcohols gave α,β-unsaturated selenoamides as a product.