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Diphenylcyclopropenone (1) reacts with enaminothiones 2 to afford 4,5-dimethylenecyclopentenone derivatives 3. The results of AMI calculations performed on both geometrically optimized 2a and the oxygen analog in the Z,s-cis-configuration favor a mechanism in which the sulfur atom of 2 acts as a nucleophile at the phenyl-C of 1.

A redução de β-enamino cetonas 1 com NaBH(OAc) 3 em ácido acético glacial produziu β-amino cetonas 3 em 65% a 67% de rendimento. Esses resultados, juntamente com outros, obtidos nas reduções de β-enamino cetonas 1 a γ-amino álcoois 2, preferencialmente syn, com NaBH 4 /HOAc, sugerem que o curso reacional desta última reação passa inicialmente pela redução de β-enamino cetonas 1 a β-amino cetonas 3 e estas são reduzidas posteriormente a γ-amino álcoois 2. Com esses resultados podemos dizer que a diastereosseletividade da redução de β-enamino cetonas 1, a γ-amino álcoois 2 dando preferencialmente produtos syn pode ser analisada como o resultado de uma competição entre um estado de transição tipo bote e um estado de transição tipo cadeira, obtidos a partir das β-amino cetonas 3.Reduction of β-enamino ketones 1 with NaBH(OAc) 3 in glacial acetic acid gave β-amino ketones 3 in 65% to 67% yield. These data and others observed in the reduction of β-enamino ketones 1 to preferentially syn γ-amino alcohols 2 with NaBH 4 /HOAc suggest that in this last reaction we have firstly the reduction of the β-enamino ketones 1 to produce the β-amino ketones 3, and then this compound is reduced to the γ-amino alcohols 2. We can say from this results that the diastereosselectivity of the reduction of β-enamino ketones 1 to mainly syn γ-amino álcohols 2, can be analysed as a competition between a chair-like transition state and a boat-like transition state, obtained from the β-amino ketones 3.

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