Stereochemistry at C-1 of geranyl pyrophosphate and neryl pyrophosphate in the cyclization to (+)- and (-)-bornyl pyrophosphate.

摘要: (1R)-1-3H-labeled and (1S)-1-3H-labeled geranyl pyrophosphate neryl were prepared from the corresponding 1-3H-labeled aldehydes by a combination of enzymatic synthetic procedures. Following admixture with 2-14C-labeled internal standard, each substrate was converted to (+)-bornyl (-)-bornyl cell-free enzyme preparations sage (Salvia officinalis) tansy (Tanacetum vulgare), respectively. Each ester hydrolyzed, resulting borneol oxidized camphor. The stereochemistry labeling at C-3 derived ketone determined base-catalyzed exchange, taking advantage known selective exchange exo-alpha-protons. By comparison such rates those product generated (1RS)-2-14C,1-3H2-labeled substrate, it demonstrated that cyclized bornyl net retention configuration C-1 acyclic precursor, whereas inversion C-1. observed is consistent reaction mechanism whereby first stereospecifically isomerized linalyl which, following rotation about C-2-C-3 cisoid conformer, cyclizes anti-endo configuration. Neryl either directly or via intermediate without attendant rotation.