Structure of 17-(3-oxazolin-4-yl)androsta-4,16-dien-3-one

Abstract

Abstract.17-(2,5-Dihydro-3-oxazol-4-yl)androsta-4,16-dien-3-one, C22H29NO2, Mr=339.48, ortho-

Formation of Stable Spiro[4.4] Ortho Ester Aminals during the Synthesis of the C26−C32 Oxazole Fragment of Calyculin C

“…The measured bond lengths of the two C(3)−N bonds are almost identical (1.439(7) Å and 1.435(6) Å). These values fit fairly well with the average C(sp 3 )−N(sp 2 ) bond length of 1.454(11) Å of acyclic amides. , The relative elongation of the C(3)−O(1) bond (bond length 1.453(7) Å) compared to the C(1)−O(1) bond (bond length 1.404(6) Å) can be explained by a weak n -σ* interaction between the N(1) lone pair and the C(3)−O(1) bond.

1 ORTEP plot of molecular structure of 4b .

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