Palladium-catalyzed ring expansion of hydroxy methoxyallenylphthalans as a novel synthetic method for highly substituted 4-isochromanone derivatives
The palladium(0)-catalyzed ring expansion reaction using hydroxy methoxyallenylphthalans (3) proceeded smoothly to give highly substituted 4- isochromanone derivatives (4), and treatment of commercially available phthalide (5) with lithium methoxyallene furnished two atom ring-expanded endo-benzoxepin-5-one (8).
Jeong, Ill-Yun,Shiro, Motoo,Nagao, Yoshimitsu
p. 85 - 89
(2007/10/03)
A new ring enlargement reaction of γ-lactones to seven-membered cyclic ethers via intramolecular endo-mode cyclisation of the ω-hydroxy allenyl ketone intermediates in situ
Phthalides 1a-f were treated with prop-2-ynylmagnesium bromide followed by treatment with 20% HCl in one pot to give the corresponding seven-membered cyclic ethers, benzoxepins 4a-f.