title: Pd(PPh(3))(4)/AgOAc-catalyzed coupling of 17-steroidal triflates and alkynes: Highly efficient synthesis of D-ring unsaturated 17-alkynylsteroids.
abstract: A novel and practical procedure was developed for the preparation of D-ring unsaturated 17-alkynyl steroids by Pd(PPh(3))(4)/AgOAc-catalyzed coupling of steroidal 17-triflates and alkynes. Firstly treatment of the steroid-17-ones with PhN(Tf)(2) and KHMDS in dried THF at -78 degrees C for 2h gives the corresponding steroidal 17-triflates products in high yields (97-98%), following the coupling of steroidal 17-triflates and various 1-alkynes by Pd(PPh(3))(4)/AgOAc-catalyzed in the presence of DIPEA for 24h to yield the desired D-ring unsaturated 17-alkynyl steroids (86-97%). Moreover, it was found that the coupling reaction catalyzed by Pd[(C(6)H(5))(3)P](4)/AgOAc system is selective for aryl triflates or vinyl triflates. By optimizing the reaction conditions, the sole C17-coupling products from steroidal bistriflates were obtained in satisfactory yields. Since D-ring unsaturated 17-alkynyl steroids with conjugated double and triplet bond can be subsequently converted into pentacyclic steroids and 17-oxosteroid derivatives at the side chain of D-ring, this general method provides a highly efficient route to these biologically important compounds.
authors.affiliation: School of Chemistry and Chemical Engineering, Yangzhou University, Siwangting Road, Yangzhou 225002, Jiangsu, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Sun
authors.forename: Chenggang
authors.initials: C
authors.lastname: Jiang
authors.forename: Hangxian
authors.initials: H
authors.lastname: Xu
authors.forename: Zonglei
authors.initials: Z
authors.lastname: Zhang
authors.forename: Lanhai
authors.initials: L
authors.lastname: Liu
authors.forename: Cunde
authors.initials: C
authors.lastname: Wang
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D013256:Steroids / Q000138:chemical synthesis* / Q000737:chemistry*; D013379:Substrate Specificity
chemical_list: D000480:Alkynes; D056831:Coordination Complexes; D013256:Steroids