摘要:
                                A novel approach to the key A-ring alpha, beta-unsaturated aldehyde 1, an important intermediate for the preparation of 1 alpha,25-dihydroxyvitamin D-3, has been developed. The strategy started from the inexpensive starting material (R)-carvone with an ene reaction serving as the key step toward the potential synthesis of vitamin D-3 analogues bearing the modification at the C-2 position.