SYNTHESIS OF 2H-PYRANO[2,3-B]QUINOLINES .2. PREPARATION AND H-1-NMR INVESTIGATIONS OF 4-HYDROXY-2-METHYL-3,4-DIHYDRO-2H-PYRANO[2,3-B]QUINOLINES

摘要

Diastereoisomers of 4-hydroxy-2-methyl-3,4-dihydro-2H-pyrano 8 and 9 were synthesized starting from the appropriate 2-chloroquinoline-3-carboxaldehydes 1. The relative configuration of the 1,3-diol intermediates 4 and 5 was determined on the basis of the C-13-nmr spectra of their acetonides. The relative stereochemistry of title compounds was confirmed by using homonuclear NOE and selective decoupling experiments, as well as by analysis of the coupling patterns observed in their H-1-nmr spectra. [References: 12]