FROM CARBOHYDRATES TO CARBOCYCLES - RADICAL ROUTES VIA TELLURIUM DERIVATIVES

D-Ribose was transformed to its protected tosylate 15, followed by a Wittig-reaction to give 16 as a 3:1 mixture of the corresponding Z and E isomers. This mixture was then transformed to the anisyltelluride 17 and the latter cyclized in a radical exchange reaction to a mixture of the carbocycles 18a and 18b (in a 17:2 ratio). The major product 18a was then transformed to various chiral cyclopentane derivatives including the cyclopentenone-derivative 23. Various other carbohydrate-based approaches have also been explored.