Structure of a dihydrooxazole oxa-bridged octalin.

C26H41NO7, Mr = 479.61, triclinic, P1, a = 11.894 (4), b = 12.360 (2), c = 9.969 (2) A, alpha = 106.11 (2), beta = 100.68 (2), gamma = 99.02 (2) degrees, V = 1349.5 (6) A3, Z = 2, Dx = 1.180 Mg m-3, Mo K alpha, lambda = 0.71069 A, mu = 0.079 mm-1, F(000) = 520, T = 296 K, R = 0.041, wR = 0.047 for 3196 observed unique reflections. A new approach to the total synthesis of the nargenicin macrolide system employing a [2,3] Wittig rearrangement to control the remote C16-C17 stereochemistry required characterization of a pivotal intermediate by X-ray single-crystal methods. The structure is characterized by the formation of strong intermolecular alcohol to dihydrooxazole-N hydrogen bonds, an essentially strain-free tricyclic oxa-bridged octalin nucleus, and low-energy conformations of the methoxymethyl ether side chains.

Prostaglandin E and F2 alpha receptors in human uterine leiomyomas.

9uman uterine leiomyomas specifically bound less (P less than 0.01) [3H]prostaglandin E1 ([3H]PGE1) and [3H] PGF2 alpha than adjacent normal myometria [leiomyomas: mean [3H]PGE1, 16.4 (range, 11.1-25.2) fmol/mg protein; mean [3H]PGF2 alpha, 4.7 (range, 0.8-12.1) fmol/mg protein; adjacent normal myometria: mean [3H]PGE1, 41.7 (range 27.1-60.7) fmol/mg protein; mean [3H]PGF2 alpha, 7.8 (range, 4.3-16.3) fmol/mg protein]. The lower binding of both [3H]PGs by leiomyomas was due to lower numbers of available high and low affinity sites. Leiomyomas and normal adjacent myometria bound 4-7 times more [3H]PGE1 than [3H]PGF2 alpha, and this appears to be due to high affinity and high numbers of low affinity PGE sites. The smooth muscle content was lower (P less than 0.01) in leiomyomas (mean, 28.0%; range, 9.7-45.5%) than that of adjacent normal myometria (mean, 58.9; range, 51.4-71.2%). In summary, this is the first demonstration of PGE and PGF2 alpha receptors in human uterine leiomyomas. Lower receptor numbers in leiomyomas appear to be due to the lower smooth muscle content of the tissue.