Intramolecular cyclization of heteroatom-containing non-conjugated unsaturated ketones by electroreduction

摘要

Electroreduction of nonconjugated enones or ynones containing a heteroatom such as a sulfur or nitrogen atom in the main chains brought about region- and stereoselective intramolecular cyclization to give the corresponding heteroatom-containing cyclic alcohols in moderate to good yields, which may be useful synthetic intermediates of biologically active compounds. Some decrease in stereoselectivity on intramolecular cyclization of N-containing nonconjugated enones may be elucidated by some disturbance of lone-pair electrons of the nitrogen atom against electronic repulsion between negative charges on the oxygen atom and the alkyl carton atom of cyclized anion radical intermediates.