- Towards chiral non-racemic cis-1,3-disubstituted cyclopentane 1,4-diphosphines
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Reaction of dialkyl- or diaryl-trans-(3,4-epoxycyclopentyl)phosphine oxides 2 with the lithium derivative of methyldiphenylphosphine oxide gives a mixture of (±)-t-4- and (±)-c-4-(disubstituted phosphinoyl)-t-2-(diphenylphosphinoylmethyl)-r-1-cyclopentanol derivatives 13a-c and 16a-c, which could be obtained in pure form by separation of the corresponding acetates 14a-c and 17a-c followed by methanolysis. Compounds 13b and 16b were transformed into the corresponding dehydroxy derivatives 19 and 21 through the Barton procedure. Additionally, 16a was transformed into a diastereomeric mixture of carbamates 22 and 23 on reaction with (S)-α-phenylethylisocyanate which could be separated by repeated crystallization. The relative configuration of compounds 13b, 17a, 21 and 22 was established by X-ray diffraction analysis.
- Camps, Pelayo,Colet, Gisela,Font-Bardia, Merce,Muoz-Torrero, Victoria,Solans, Xavier,Vazquez, Santiago
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p. 759 - 778
(2007/10/03)
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- Radical Reactions of Bicyclopentane
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The photochemical reactions of bicyclopentane with bromine, bromotrichloromethane, t-butyl hypochlorite, di-t-butyl peroxide, and N-bromosuccinimide have been investigated.Trichloromethyl, t-butoxyl, and succinimidyl radicals abstract hydrogen from the C4 ring.The expected bicyclopentyl radicals were not detected and if they are discrete intermediates they must rearrange by fission of the C(1)-C(4) bond common to the two rings to form cyclopent-3-enyl radicals.The e.s.r. spectrum of the latter radicals was obtained.Bromine (and chlorine) atoms may abstract hydrogen, but their major pathway involves attack at the bridgehead carbon atoms in an SH2 reaction with fission of the C(1)-C(4) bond to give 3-halogenocyclopentyl radicals.
- Jamieson, Campbell,Walton, John C.,Ingold, Keith U.
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p. 1366 - 1371
(2007/10/02)
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