A practical asymmetric synthesis of a 1,7-enyne A-ring synthon en route toward the total synthesis of vitamin D3 analogues

Article abstract of DOI:10.1016/0040-4039(94)88259-2

A concise synthesis of a key A-ring synthon of 1α,25-dihydroxyvitamin D₃, 1, has been achieved in 8 steps starting from readily available, inexpensive ethyl-4-chloroacetoacetate. This synthon serves as one of two main coupling partners in our previously developed Pd-catalyzed alkylative enyne cyclization leading toward the total synthesis of la,25-dihydroxyvitamin D₃ and potentially useful analogues.