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Digitale Medien

Can circularly polarized light be used to obtain chiral compounds of high optical purity? (1974)

Kagan, H. B. ; Balavoine, G. ; Moradpour, A.

Springer

Journal of molecular evolution 4 (1974), S. 41-48

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ISSN: 1432-1432

Schlagwort(e): Circularly Polarized Light ; Asymmetric Synthesis ; Kinetic Photoresolution ; Optical Purity ; Helicene ; Generation of Optical Activity

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary The production of optically active compounds starting from optically inactive material and with the help only of circularly polarized light is briefly discussed. This problem is possibly related to the appearance of optical activity on earth. Some aspects of photochemical asymmetric synthesis of helicenes are given, the optical yields being always lower than 1%. The possibility of obtaining much higher optical purity by using partial asymmetric photodecomposition of a racemic mixture is then discussed. The kinetic treatment allows the prediction that at the end of the destruction the recovered material must be of high optical purity. An experimental demonstration of the correctness of the calculations is shown in the case of dl camphor. Camphor of 20% optical purity could be isolated after prolonged photolysis by circularly polarized light.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01732770

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Digitale Medien

Synthesis of tertiary phosphine oxides mediated by SmCp2 or Sml2 (1995)

Dallemer, F. ; Collin, J. ; Kagan, H. B.

New York, NY [u.a.] : Wiley-Blackwell

Applied Organometallic Chemistry 9 (1995), S. 431-435

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ISSN: 0268-2605

Schlagwort(e): samarium di-iodide ; divalent samarium ; samarium dicyclopentadienide ; phosphine oxide ; Michael additions ; diphenyl alkyl phosphine oxide ; phenyl dialkyl phosphine oxide ; Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Tertiary phosphine oxides are prepared under mild conditions by sequential addition of diphenylphosphinoyl chloride to divalent samarium compounds (SmCp2 and SmI2) followed by reaction with various electrophiles such as organic halides, tosylates, epoxides or α,β-unsaturated ketones. Biscyclopentadienylsamarium (SmCp2) gives better yields than SmI2. Similar reactions, using phenylphosphonoyl dichloride, SmI2 and subsequent addition of two equivalents of activated halides, yield the corresponding tertiary phosphine oxides.

Zusätzliches Material: 1 Tab.