@article{d90db568e2a3450bbf68ce59c5662310,
title = "Synthesis of the necine bases (±)-macronecine and (±)-supinidine via an aza-ene reaction and allylsilane induced ring closure",
abstract = "An aza-ene reaction has been used for the first time for the synthesis of two 5-membered lactam-hydrazides, each with a built-in allylsilane terminator for further elaboration. One of the lactam-hydrazides was transformed via an allylsilane-hydrazonium ion ring closure to a fused tetrahydropyrazole which may be considered as a mono-nitrogen analog of the biologically significant necine bases. A density functional theoretical study (B3LYP/6-21G*) was undertaken to provide insight into the factors that favor a synclinal transition structure of the hydrazonium ion intermediate leading to the tetrahydropyrazole. This stereocontrolled synthesis served as a model for the multi-step conversion of the other lactam-hydrazide, the substituted 2-pyrrolidinone, to necine bases (±)-supinidine and (±)- macronecine. An allylsilane-aldehyde ring closure formed the key step in the synthesis of these natural products.",
keywords = "Aza-ene reaction, Fused tetrahydropyrazole, Heterocyclic allylsilanes, Macronecine, Necine bases, Supinidine",
author = "Sarkar, {Tarun K.} and Anindya Hazra and Pulak Gangopadhyay and Niranjan Panda and Zdenek Slanina and Lin, {Chun Cheng} and Chen, {Hui Ting}",
note = "Funding Information: Financial support from DST, Government of India is gratefully acknowledged. A. H. and N. P. thank CSIR, Government of India for a Senior Research Fellowship. Z. S. acknowledges support from the Japan Society for the Promotion of Science. We thank Professor S. E. Denmark for providing us with copies of 1 H and 13 C NMR spectra of (−)-macronecine. We also thank Professor D. Hart for sending us the copy of 1 H NMR of (±)-supinidine. Professor D. L. J. Clive is thanked for help with X-ray crystallographic work. Dr. S. K. Ghosh (BARC, India) is especially thanked for continued help. ",
year = "2005",
month = jan,
day = "31",
doi = "10.1016/j.tet.2004.11.046",
language = "English",
volume = "61",
pages = "1155--1165",
journal = "Tetrahedron",
issn = "0040-4020",
publisher = "Elsevier Limited",
number = "5",
}