Synthesis of Carbasugar C-1 Phosphates via Pd-Catalyzed Cyclopropanol Ring Opening

Abstract

The stereoselective syntheses of 2,3-dideoxy-4-oxo-5a-carba-α-d-rhamnopyanose 1-phosphate, 2,3-dideoxy-5a-carba-α-d-rhamnopyranose 1-phosphate, 5a-carba-α-d-rhamnopyranose 1-phosphate, 5a-carba-β-d-digitoxopyranose 1-phosphate, and 5a-carba-α-l-rhamnopyranose 1-phosphate have been achieved from d-quinic acid. The routes rely upon a Simmons−Smith cyclopropanation and diastereospecific ring opening of cyclopropanol under Pd/C hydrogenation condition to set up the α-methyl ketone. A sequence of diastereoselective reduction, dihydroxylation, and/or Myers’ reductive 1,3-rearrangement were used to install the desired stereochemistry.