Thiophenes metal carbonyl derivatives

The metal-ammonia reduction of thiophene and its derivatives has formed part of a review (76H(5)905). The formation of hydrogenation products requires the presence of a proton source otherwise only fission products are observed. In the presence of methanol the major products from thiophene are (196) and (197), the latter undergoing further cleavage as shown in Scheme 40. With Li/NH3 or Na/NH3, alkylthiophenes undergo cleavage, the usual work-up leading to carbonyl compounds as shown in Scheme 41. 

Thienyl-lithium derivatives prepared through halogen-metal exchange and containing acetal-protected carbonyl groups have been used in the synthesis of di- and tri-formyl derivatives of thiophen, t-butoxy-sub-stituted thiophen aldehydes, and formylacetylthiophens. Symmetrical thienyl-substituted ketones have been obtained from thienyl-lithium derivatives and carbamates. " Mixed heterocyclic carbinols have been obtained through the reaction of thienyl-lithium derivatives with heterocyclic aldehydes. Thienyl-lithium derivatives react with cyclohexanone, and various phenylthiophens have been made by aromatization of the intermediate cyclohexenyl derivative. The reaction of thienyl-lithium derivatives with NN-dimethylacetamide, which has been used for the synthesis of... 

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