Douglas H. Rector

Palladium/hydrogen catalyzed alcoholysis of benzylsilanes

Abstract Certain benzylsilanes are converted to methoxy or ethoxysilanes and toluene when treated with methanol or ethanol in the presence of hydrogen and catalytic amounts of palladium on charcoal. The reaction is promoted by a Si-phenyl substituent and probably by a S N Si displacement mechanism.

Synthesis and crystal and molecular structure of a 1,11-methano-steroid, 3-methoxy-1′β-methyl-1,11α-methano-9β-estra-1,3,5(10)-trien-17β-ol

Treatment of 17,17-ethylenedioxy-3-methoxy-11α-vinylestra-1,3,5(10)-trien-11β-ol with various acids afforded 3-methoxy-1′β-methyl-1,11-methanoestra-1,3,5(10),9(11)-tetraen-17-one, and not the isomeric 1,11-ethanosteroid. Birch reduction of this pentacyclic product gave the title compound, the structure of which was established by X-ray single-crystal analysis. Crystals are orthorhombic, space group P212121, with a= 9.153(5), b= 17.918(10), c= 10.200(5)A, Z= 4. The structure was solved by direct methods and refined by full-matrix least-squares calculations to R 0.046 over 1474 statistically significant reflections from diffractometer measurements. The steroid skeleton is folded severely to the α-side about the C(8)–C(9) bond. Ring B adopts a distorted half-chair conformation, ring C has a chair form significantly flattened around C(9), and ring D approximates to a C(13)-envelope.

Synthesis, crystal and molecular structure of a 1,11-etheno-steroid: 3-methoxy-1,11-ethenoestra-1,3,5(10),9(11)-tetraen-17-one

Methods of construction of a two carbon bridge between C(1) and C(11) of the steroid skeleton have been studied. Treatment of 17,17-ethylenedioxy-11α-ethynyl-3-methoxyestra-1,3,5(10)-trien-11β-ol (2) with toluene-p-sulphonic acid in benzene gave a mixture of 3-methoxy-1′ξ-methyl-1,11ξ-methanoestra-1,3,5(10),6,8,-pentaen-17-one (7) and the title compound (8). The latter was also obtained in poor yield from 17,17-ethylenedioxy-3-methoxy-11α-(2-oxoethyl)estra-1,3,5(10)-trien-11β-ol (4) in hydrogen fluoride and in better yield (76%) from treatment of (2) with tris(triphenylsilyl) vanadate. Crystals of (8) are orthorhombic, space group P212121, a= 7.867(5), b= 30.036(20), c= 6.838(5)A, Z= 4. The structure was solved by direct methods and refined by full-matrix least-squares calculations to R 0.044 over 1 283 statistically significant reflections from diffractometer measurements. The modified steroid skeleton is very flat, the maximum deviation of any ring atom from the naphthalene plane being 0.635 A. Ring B approximates to a C(7)α-envelope form, ring C adopts a half-chair conformation, and ring D has a C(14)α-envelope form.