... [13] RR Gupta, M. Kumar and V. Gaupta, Heterocyclic Chemistry, Vol. 2, Springer, New York, (1999), pp. 421. ... [17] FA Carey and R. J. Sundberg, Advanced Organic Chemistry, Part B: Reactions and Synthesis, 3rd edition, Plenum Press, New York, (1990), pp. 587. ... J. Med. Chem. ...