Silver mediated acetylenic oxy cope rearrangement

✍ Scribed by Norbert Bluthe; Jacques Gore; Max Malacria

• Book ID: 104204488
• Publisher: Elsevier Science
• Year: 1986
• Tongue: French
• Weight: 574 KB
• Volume: 42
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)87352-x

✦ Synopsis

Electrophile initiated acetylenic oxy Cope rearraqemmt of divmelysubstituted 5-Hcxen-1-yn-3-01s leads to the cwrespuWgaC6 -diethylmlc aldehydes or ketones In 9ood yields wlth mainly the E conf iguraticn fw both tile bonds. Silver nitrate and Silver triflwromethanesulfonate appear to be the most suitable electrophiles for this purpose and can be used either ctoichiornetrically (AgTf)or catalytically (AgNo3). The thermal oxy-Cope rearrangement of 1,5-hexadiene-3-01s to Sethylmic ketones is IKW a long known process (1) but its synthetic utility either for the elongation of open chain compounds cr for the four-carbon homologatlcn of cyclic systems is considerably reduced owing to a low stereoselectivity and mainly to a competing cleavage of the molecule due to an ene process lnvolvlog the hydroxyl qwp (2). In recent years, the potential of this [3.3] signstropic transposition has been highly increased by the development of new conditions that eliminate the cleavage side-reaction and Increase markedly Its stereoselectivity. Some of them. for example. the siloxy-Cope reerraqpment (3). uu derivatives of the st#ting dienol but the more interesting ones are those which start from the alcohol ltsslf and aoceleratc the oxy-Cope process by qrotic polar solvents (4) cr by tramfaming it to the potassiun almholate (5).

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