Patent ID: 8227629
Filing Date: 2012-07-24
Classification: C07C,C07D

Abstract:
1. A process for the preparation of a furan of formula wherein the dotted line is a single bond and n is 1 or the dotted line is a double bond and n is 0, in the form of a racemic or optically active diastereoisomer, wherein the substituents in the positions 9a, 9b and 3a are in a relative configuration cis, and the hydrogen atom in position 5a and the oxygen atoms are in configuration trans relative to the methyl in position 9a; wherein the process comprises: A) rearranging a propargylic alcohol of formula  wherein the dotted line and n have the same meaning as indicated for compound (I), in the form of a racemic or optically active compound wherein, if n is 1, the methyl in position 9a and the hydrogen atom in position 5a is in a relative trans configuration; to obtain an aldehyde of formula  wherein the dotted line and n have the same meaning as indicated for compound (I), in the form of a racemic or optically active compound wherein, if n is 1, the methyl in position 9a and the hydrogen atom in position 5a is in a relative trans configuration; B) reducing the aldehyde of formula (III) into the corresponding alcohol of formula  wherein the dotted line and n have the same meaning as indicated for compound (I) and, if n is 1, being in the form of a racemic or optically active diastereoisomer wherein the methyl in position 9a and the hydrogen atom in position 5a are in the relative trans configuration; C) cyclizing compound (IV) into the corresponding furan of formula (I).