Vinylogous dieckmann condensation: an application of Baldwin's rules.

✍ Scribed by Montree Kodpinid; Yodhathai Thebtaranonth

• Book ID: 104233587
• Publisher: Elsevier Science
• Year: 1984
• Tongue: French
• Weight: 198 KB
• Volume: 25
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)81218-1

✦ Synopsis

Vinylogous Dieckmann condensations equivalent to enolexo-exo-trig and enolendo-exo-trig cyclisations have been investigated. Five membered rings were smoothly obtained from the former whereas the latter cyclisations occurred with six but not with five membered ring systems. The Dieckmann condensation (equation i) has recently been described by Baldwin as an n-(enolexo)-exo-trig cyclisation, and a "&zwoumd ~LOCUA". 132 However, cyclisations such as 3 4 that depicted in equation ii have been concluded, independently by both House and Baldwin , to be of the enolendo type, and is dependent on the value of n. Accordingly, a base catalysed cyclisation of S-halo-2-pentanone would be difficult, and the reaction is described as a 0 c C OR . . . . ...(i)