Intramolecular 4+3 cycloadditions. Allylic sulfones as precursors to vinylthionium ions

✍ Scribed by Michael Harmata; Mehmet Kahraman

• Book ID: 104259210
• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 220 KB
• Volume: 39
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(98)00582-6

✦ Synopsis

Treatmen~ of a THF solution of (E)-3 with n-BuLi followed by quenching with an electrophile generally re:mRs in regioselective alkylation alpha to the sulfone with the alkene possessing (E) stereochemistry in the major product. High selectivity for the (E) alkylation product can he achieved in the presence of small amounts of HMPA. When those (E) alkylation products possessing a diene moiety in the side chain are treated with Lewis acids, 4+3 cycloaddition products are formed in good to excellent yields.