Reaction of a polymerization‐resistant 1,2‐dithiolane with lithiated nitrogen heterocycles

Nitrogen-containing five-membered heterocycles, N-methylpyrrole 2, N-methylpyrazole 4, N-methylimidazole 6, 4-methylthiazole 11, N-methylindole 14, benzothiazole 16, N-methylbenzimidazole 18, and benzoxazole 20 were lithiated with BuLi and LDA in THF and reacted with the polymerization-resistant 1,2-dithiolane 1. All of the corresponding lithioheterocycles cleaved the S–S bond of the 1,2-dithiolane 1 to give the ring-opened products in line with the carbanion mechanism proposed for the enzyme-reductive acylations of lipoic acid. The ring-opened products 8, 9, 13, 22, and 23 were isolated in good yields and high purity. The ring-opened products from benzothiazole and N-methylbenzimidazole were decomposed by the action of excess lithioheterocycles. The lithiobenzoxazole was less reactive than the other lithioheterocycles. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:289–294, 1998