Question

Discuss the synthesis of following compounds using retrosynthtic analysis:

Vitamin D and Camphor.

Answer 1

2-alkylated 1a,25-dihydroxy-19-norvitamin D as the active part. The CD ring synthon 3

was converted from 25-hydroxy Grundmann’s

ketone (4) via E-selective Horner–Wadsworth–

Emmons carboxyolenation followed by reduc-

tion.