The Journal of Organic Chemistry

An intramolecular Diels-Alder approach to the cis ring fused isomer of the 25-hydroxy vitamin D2 Grundmann ketone

SR Wilson, L Jacob

Index: Wilson, Stephen R.; Jacob, Linda Journal of Organic Chemistry, 1992 , vol. 57, # 16 p. 4380 - 4385

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Citation Number: 8

Abstract

Stereospecific Claisen and intramolecular Diels-Alder reactions of chiral ester synthon 4 resulta in conversion of a single asymmetric center of commercially available ester 4 to a vitamin D synthon, the C/D cis Grundmann ketone 3. The addition of propenyllithium to aldehyde 9 was dominated by a chelated anti-Cram transition state and yielded the threo isomer 128 as the major product. The stereochemistry of 12a was determined by X-ray ...