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Lewis acid mediated cyclisation of methylenecyclopropyl ketones and aldehydes

โœ Scribed by Guillaume L.N. Peron; John Kitteringham; Jeremy D. Kilburn

Book ID
104261114
Publisher
Elsevier Science
Year
1999
Tongue
French
Weight
191 KB
Volume
40
Category
Article
ISSN
0040-4039

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โœฆ Synopsis

The Lewis acid mediated cyclisation of various methylenecyclopropyl ketones, ketals and aldehydes has been investigated as a new route to six-and seven-membered rings. Cyclisation of aldehyde 6, ketal 9 and ketone 11 with TiCI 4 gave cyclohexene products, and cyclisation of ketal 10 gave a dichlorocycloheptene, all via nucleophilic addition of the methylenecyclopropyl n bond to the activated carbonyl. Cyclisation of ketone 12, however, with SnC14, gave a cyclopentanol 21, presumably via nucleophilic addition of a cyclopropyl ~ bond to the activated carbonyl.

๐Ÿ“œ SIMILAR VOLUMES

Lewis acid-promoted addition of methylen
Lewis acid-promoted addition of methylenecyclopropanes to aldehydes and ketones
โœ Katsukiyo Miura; Mizuki Takasumi; Takeshi Hondo; Hiroshi Saito; Akira Hosomi ๐Ÿ“‚ Article ๐Ÿ“… 1997 ๐Ÿ› Elsevier Science ๐ŸŒ French โš– 242 KB

In the presence of TiCi4, me~ylenecyclopropane (la) easily reacted with Jdln~u~tlc aldehydes to give the p-(chiorome~yl)allylate~ products 2 in good yields along with a small amount of the methylenetetrahydrofurans 3. The reacti~ with chiral a-and ~-alkoxy aldehydes lwoceeded with high levels of cl~