Conformational analysis by carbon-13 nuclear magnetic resonance spectroscopy. Part I. Hexahydro-3H-oxazolo[3,4-a] pyridines

Abstract

Compraison of the C(3), C(1), and C(8a) chemical shifts in hexahydro-3H-oxazolo [3,4-a] pyridine with those in methyl substituted derivatives suggests its existence in solution at n.m.r. probe temperature as a cis⇌trans equilibrium mixture containing 73–78% of the trans-fused conformation; ¹³C–H coupling constants involving the C(3) protons are dependent upon the orientation of adjacent heteroatom lone pairs.