Novel and efficient synthesis of 22-alkynyl-13,24(23)-cyclo-18,21-dinorchol-22-en-20(23)-one analogues.

The efficient synthesis of some 22-alkynyl-13,24(23)-cyclo-18,21-dinorchol-22-en-20(23)-ones was investigated. 22-Iodocyclo-18,21-dinorcholenones were prepared from cyclo-18,21-dinorcholenones using I(2)/DMAP/pyridine system firstly. The cross coupling reaction of 22-iodocyclo-18,21-dinorcholenones and 1-alkynes was carried out efficiently catalyzed by tetrakis(triphenylphosphine) palladium/cuprous iodide in the presence of base diisopropylethylamine. This strategy offered a very straightforward and efficient method for access to conjugated alkynyl cyclo-18,21-dinorcholenones from the cyclo-18,21-dinorcholenones and 1-alkynes in excellent overall yields. Evaluation of the synthesized compounds for cytotoxicity against KB, HeLa, MKN-28 and MCF-7 cell lines showed that the 22-alkynylcyclodinorchoenones possessing hydroxylethyl and hydroxylmethyl mono-substituted side chain at the end of alkynyl group have significantly inhibition activity.

Pd(PPh(3))(4)/AgOAc-catalyzed coupling of 17-steroidal triflates and alkynes: Highly efficient synthesis of D-ring unsaturated 17-alkynylsteroids.

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.