Synthesis of benzofuran derivatives-II: a new synthesis of visnagin

Aneja, R. ; Mukerjee, S. K. ; Seshadri, T. R. (1958) Synthesis of benzofuran derivatives-II: a new synthesis of visnagin Tetrahedron, 3 (3). pp. 230-235. ISSN 0040-4020

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Official URL: http://www.sciencedirect.com/science/article/pii/0...

Related URL: http://dx.doi.org/10.1016/0040-4020(58)80018-6

Abstract

Starting with 2-methyl-5:7-dihydroxychromone, an allyl group is introduced into the 6-position by Claisen migration of a 5-allyl ether. The initial protection of the 7-hydroxyl is best effected by tosylation. If the tosyl group is removed before Claisen migration and the C-allyl compound subjected to ozonolysis and ring closure, norvisnagin is obtained in a poor yield and can be methylated to visnagin. In an alternative method the tosyl group is removed just before ozonolysis. For this purpose the previous methylation of the 5-position is advantageous. This route gives visnagin directly in good yield.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
ID Code:68242
Deposited On:02 Nov 2011 11:15
Last Modified:02 Nov 2011 11:15

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