GhatakA., BeckerF. F., and BanikB. K., Tetrahedron Lett., 2000, 41, 3793.
15.
MoodyC.J., and PittsM. R., Synlett, 1998, 1028. Also see: (a) B.K. Banik, M. Suhendra, I. Banik and F.F. Becker, Synth. Commun. 2000.
16.
BanikB.K., HackfieldL., and BeckerF. F., Synth. Commun., 2000.
17.
For an example of the beneficial effect of ultrasonic irradiation, see: HanB.H., and BoudjoukP., J. Org. Chem., 1982, 47, 5030.
18.
A representative procedure is as follows: To a solution of ketone (0.5 mmol) in methanol (10 ml), solid ammonium chloride (2.5 mmol) and samarium metal (1.1 mmol, 40 mesh) was added and the reaction mixture was sonicated10 at room temperature for 5 min. The reaction started immediately as indicated by the evolution of gas and change of colour of the reaction mixture from colorless to greenish yellow. After the reaction was completed as indicated by TLC, the total volume of the reaction mixture was reduced (ca 2ml) by evaporation under reduced pressure. Water (5 ml) was added to the residue and the reaction mixture was extracted with dichloromethane (3 × 5 ml). The organic layer was dried over sodium sulfate and concentrated. The pure product was obtained by column chromatography using ethyl acetate and hexane as the solvent. All products have been characterized through mass and NMR spectra and direct comparison with authentic samples prepared earlier in this laboratory.6
19.
A. Bransonic Model 2210R-DTH was used for sonication.
