Abstract
A highly catalytic method for the synthesis of dihydrobenzopyrans from salicylaldehydes has been developed. An extension of this method to the synthesis of a pyrano[2,3,b]benzopyran has also been achieved. Bi(OTf) 3•xH 2O (1 < x < 4) (0.1 mol%) smoothly catalyzes the condensation of substituted salicylaldehydes with 2,2-dimethoxypropane to give the corresponding substituted 3,4-dihydro-2H-1- benzopyrans as a mixture of diastereomers (9:1) in moderate yields. The relative configuration of the methoxy groups in the two diastereomers was established by NOE experiments. The advantages of this method include the use of an easy to handle, inexpensive and relatively non-toxic catalyst.
Original language | English (US) |
---|---|
Pages (from-to) | 9369-9371 |
Number of pages | 3 |
Journal | Tetrahedron Letters |
Volume | 45 |
Issue number | 51 |
DOIs | |
State | Published - Dec 13 2004 |
Bibliographical note
Funding Information:We gratefully acknowledge funding from the National Science Foundation (RUI grant # 0350216). R.S.M. is also indebted to The Camille Henry Dreyfus foundation for a Henry Dreyfus Teacher Scholar award.
Keywords
- Bismuth and compounds
- Bismuth triflate
- Dihydrobenzopyrans
- Green chemistry