ChemInform Abstract: Preparation of Optically Active Secondary Amines by Thermal Decomposition of (Methylbenzyl)urea Analogs: Absolute Configuration of (+)- and (-)-Mecamylamine.

1986 ◽  
Vol 17 (24) ◽  
Author(s):  
B. SCHOENENBERGER ◽  
A. BROSSI ◽  
C. GEORGE ◽  
J. L. FLIPPEN-ANDERSON
Keyword(s):  
Thermal Decomposition ◽  
Absolute Configuration ◽  
Optically Active ◽  
Secondary Amines

Thermal decomposition of optically active unsymmetrical azoalkanes. (−)-(S)-1,1′-Diphenyl-1-methylazomethane

1969 ◽  
Vol 47 (13) ◽  
pp. 2371-2386 ◽  
Author(s):  
Karl R. Kopecky ◽  
Thomas Gillan
Keyword(s):  
Thermal Decomposition ◽  
Absolute Configuration ◽  
Simple Expression ◽  
Optically Active ◽  
Cage Effect ◽  
Benzyl Radical ◽  
Solvent Cage ◽  
Optically Pure ◽  
Cage Effects ◽  
Partial Retention

The ratio, (Kc/Kr)cage, of the rate of coupling of the 1-phenylethyl radical with the benzyl radical to the rate of its rotation with respect to the benzyl radical in the solvent cage has been determined for several solvents. The optically pure title compound, (−)-(S)-4, has been prepared and its absolute configuration determined. Thermal decomposition of (−)-(S)-4 yields (−)-(R)-1,2-diphenylpropane, (−)-(R)-9, with partial retention of configuration. The maximum rotation of (−)-(R)-9 has been determined. At 100° in benzene, cyclohexane, chlorobenzene, (all containing ca. 1 M butanethiol) and butanethiol, the cage effects for the decomposition of (±)-4 were found to be 28.3, 31.7, 33.4, and 18.2%, respectively. Under these conditions (−)-(R)-9 was formed from (−)-(S)-4 with 10.3, 10.9, 13.0, and 17.3% net retention of configuration, respectively. A simple expression for (Kc/Kr)cage can be derived:[Formula: see text]F is the fraction of radicals consumed within the solvent cage and f is the fraction of radicals consumed within the solvent cage that disproportionate. Under the above conditions values for (Kc/Kr)cage were found to be 0.059, 0.069, 0.090, and 0.070, respectively. The values of the cage effect and (Kc/Kr)cage given were calculated assuming f = 0.1, but change little if f is assumed to be 0. The relevance of these results to the stereochemistry of the Wittig and Meisenheimer rearrangements and of the decomposition of diacyl peroxides is discussed.

Absolute configuration determination of some optically active multifunctional carbon compounds

1988 ◽  
Vol 29 (37) ◽  
pp. 4727-4730 ◽  
Author(s):  
Yoshio Takeuchi ◽  
Michiyo Nojiri ◽  
Toru Koizumi ◽  
Yoichi Iitaka
Keyword(s):  
Absolute Configuration ◽  
Optically Active ◽  
Carbon Compounds

Optically Active Seleninamides:  Isolation, Absolute Configuration, and Racemization Mechanism

2005 ◽  
Vol 70 (3) ◽  
pp. 868-873 ◽  
Author(s):  
Yusuke Nakashima ◽  
Toshio Shimizu ◽  
Kazunori Hirabayashi ◽  
Nobumasa Kamigata
Keyword(s):  
Absolute Configuration ◽  
Optically Active

scholarly journals PREPARATION OF OPTICALLY ACTIVE 1,6,12c,12d-TETRAMETHYL-12c,12d-DIHYDROCORONENE WITH KNOWN ABSOLUTE CONFIGURATION

1984 ◽  
Vol 13 (11) ◽  
pp. 1977-1978 ◽  
Author(s):  
Koji Yamamoto ◽  
Tatsuo Ueda ◽  
Hiriya Yumioka ◽  
Yoshio Okamoto ◽  
Toshikatsu Yoshida
Keyword(s):  
Absolute Configuration ◽  
Optically Active

Synthesis and resolution of an asymmetric arsonium cation. Crystal and molecular structures of (R)-Benzyl(methyl)(4-methylphenyl)(naphthalen-1-yl)- arsonium bromide and hexafluorophosphate

1984 ◽  
Vol 37 (6) ◽  
pp. 1171 ◽  
Author(s):  
DG Allen ◽  
CL Raston ◽  
BW Skelton ◽  
AH White ◽  
SB Wild
Keyword(s):  
Ion Exchange ◽  
Absolute Configuration ◽  
Optically Active ◽  
Molecular Structures ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Crystal And Molecular Structures ◽  
Ion Exchange Column ◽  
Optically Pure

The (�)-benzyl(methyl)(4-methylphenyl)(naphthalen-1-yl)arsonium cation has been synthesized and subsequently resolved by fractional crystallization of monohydrogen [R-(R*,R*)]-2,3-bis(benzoyloxy)- butanedioate salts. The separated diastereoisomers were converted into the corresponding optically active arsonium bromides by ion-exchange column chromatography. The absolute configuration of the arsonium cation exhibiting a positive rotation at 589 nm (sodium D line) has been established as (R) by single-crystal X-ray analysis of both the bromide and hexafluorophosphate salts. The arsonium bromide with [α]D + 54.8�(c, 0.62 in CH2Cl2) crystallizes in the orthorhombic space group P212121 (D24, No.19) with a 22.472(8), b 15.724(7), c 12.585(5) � and U 4447(3) �3. The corresponding hexafluorophosphate with [α]D + 19.3� (c, 0.5 in CH2Cl2) crystallizes in the same space group with a 23.56(2), b 16.40(1), c 13.12(1) � and U 5067(6) � 3. Benzylidene transfer to benzaldehyde from the arsonium ylide derived from either of the arsonium salts produced optically pure (–)-(S)-methyl(4-methylphenyl)(naphthalen-1-yl)arsine, [α]D - 115.9� (c, 0.593 in CHCl3), and partly resolved [R-(R*,R*)]-2,3-diphenyloxiran.

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