Preparation and alkylation of cyclic β-trimethylstannyl α,β-unsaturated esters. A new, general annulation sequence

✍ Scribed by Edward Piers; Lun Allan Tse Hoi

• Publisher: Elsevier Science
• Year: 1984
• Tongue: French
• Weight: 218 KB
• Volume: 25
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)90996-7

✦ Synopsis

The key steps of a newly developed annulation method involve (a) reaction of cyclic S-trifluoromethanesulfonyloxy a,S-unsaturated esters (e.g. 14-16) with lithium --(phenylthio)(trlmethylstannyl)cuprate, (b) alkylation of the resultant products (e.g. 17-19) -with l,wdihaloalkanes, and (c) transmetalation-cyclization of suitable substrates (e.g. 2, 2, 2, 30) derived from the alkylation products (e.g. 20-24).

--Annulation methods, involving the construction of rings onto cyclic or acyclic substrates, have been, and continue to be, of great importance in synthetic organic chemistry. Indeed, it is difficult to overstate the centrality of such processes in the area of natural product synthesis. Since the introduction of the Robinson annulation sequence