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Novel Regio‐ and Stereoselective Cascade 6‐ endo ‐trig Cyclisations from Polyene Acyl Radical Intermediates Leading to Steroid‐Like Pentacycles and Heptacycles
Author(s) -
Handa Sandeep,
Nair Prathap S.,
Pattenden Gerald
Publication year - 2000
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20000906)83:9<2629::aid-hlca2629>3.0.co;2-w
Subject(s) - chemistry , polyene , stereoselectivity , steroid , stereochemistry , cascade , organic chemistry , catalysis , biochemistry , chromatography , hormone
In a quite remarkable regio‐ and stereoselective manner, each of the (all‐ E )‐polyene selenoates 5a – c is shown to undergo cascade radical‐mediated polycyclisations via consecutive 6‐ endo ‐trig reactions, leading to the corresponding all‐ trans , anti , tri‐, penta‐ and heptacycles, i.e. , 20 , 23 , and 25 , in good yields. The configurations of these `steroid‐like' polycycles followed from detailed examination and correlation of chemical shift data in their 13 C‐NMR spectra.