title: Pd-catalyzed carbocyclization-Negishi cross-coupling cascade: a novel approach to 1alpha,25-dihydroxyvitamin D3 and analogues.
abstract: [reaction: see text] A mild palladium-catalyzed cascade has been used for the synthesis of the hormone 1alpha,25-dihydroxyvitamin D3 (calcitriol, 1a) and its analogues 1b and 1c. This one-pot process involves two consecutive transformations at room temperature: An initial palladium-catalyzed 6-exo-cyclocarbopalladation of vinyl triflates followed by a Negishi cross-coupling reaction with an alkenyl zinc. This novel strategy opens new possibilities for the preparation of a variety of new vitamin D analogues of therapeutic potential, particularly with modifications at the triene and/or ring-A.
authors.affiliation: Departamento de Química Orgánica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain.
authors.forename: Clara
authors.initials: C
authors.lastname: Gómez-Reino
authors.forename: Cristian
authors.initials: C
authors.lastname: Vitale
authors.forename: Miguel
authors.initials: M
authors.lastname: Maestro
authors.forename: Antonio
authors.initials: A
authors.lastname: Mouriño
mesh_terms: D002384:Catalysis; D003500:Cyclization; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000138:chemical synthesis
chemical_list: C118756:dihydroxy-vitamin D3; D014807:Vitamin D; D010165:Palladium