Efficient preparation of 4-methoxy-5,6-dihydro-2H-pyran

2008

Abstract We report the efficient synthesis of 4-methoxy-5,6-dihydro-2 H -pyran (MDHP) via the TiCl 4 driven elimination of MeOH from 4,4-dimethoxytetrahydropyran. The previous difficulty of preparing MDHP restricted the wider use of 4-methoxytetrahydropyran-4-yl (MTHP) acyclic acetals, which have desirable protecting group properties when compared to more commonly used MOM- and THP-acetals. The behaviour of the elimination on related acetals is also examined.