Furan Approach to Vitamin D Analogues. Synthesis of the A-Ring of Calcitriol and 1α-Hydroxy-3-deoxyvitamin D<sub>3</sub>
                                
                                    
                                        作者:William H. Miles、Katelyn B. Connell、Gözde Ulas、Hannah H. Tuson、Elizabeth A. Dethoff、Varun Mehta、April J. Thrall                                    
                                    
                                        DOI:10.1021/jo101155c
                                    
                                    
                                        日期:2010.10.15
                                    
                                    The A-rings of calcitriol (1 alpha,25-dihydeoxyvitamin D-3) and 1 alpha-hydroxy-3-deoxyvitamin D-3 were synthesized using the furan approach The critical steps in the synthesis of the A-ring of calcitriol involved an asymmetric carbonyl-ene reaction of 3-methylene-2,3-dihydrofuran with 3-(tert-butyldimethylsiloxy)-propanal. a diostereoselective Friedel-Crafts hydroxyalkylation an oxidation of the 2.3-disubstituted furan to give a gamma-hydroxybutenolide and a Peterson olefinatiion The A-ring (Z)-dienol of calcitriol was synthesized in 12 steps from 3-(tert-butyldimethylsiloxy)propanal in 17% yield