A novel synthesis of cyclopentenones and cyclohexenones via cycliacylation of lithioalkenylcarboxamides

✍ Scribed by Hiroyuki Sawada; Michael Webb; A.Timothy Stoll; Ei-ichi Negishi

• Book ID: 104218212
• Publisher: Elsevier Science
• Year: 1986
• Tongue: French
• Weight: 228 KB
• Volume: 27
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)84098-8

✦ Synopsis

The reaction of 1-iodo-3-bromopropene derivatives (l_) with lithium enolates of N,fl-dialkylcarboxamides followed by treatment of the allylation product (2) with two equiv of t-BuLi cleanly provides cyclopentenones in high yields, while the corresponding cycliacylation reaction of 6-iodo-5hexenamides provides cyclohexenones. 1-Iodo-3-halopropene derivatives (I), readily obtainable via hydrometalation3 or carbo-metalation4 of propargylic alcohols appear attractive as three-carbon synthons for the synthesis of cycloalkenes. Although some reports have described their use in the synthesis of butyrolactones,5 little, if any, appeared to be known about their use in the synthesis of carbocycles.

We recently reported a mild and selective method for converting 1_ into cyclopropenes (eq 1).