Electrocyclic ring opening of 1α,4α- and 1α,4β-bicyclo[2.2.0]hexa-2,5-dienes (cis and trans Dewar benzenes): MNDO (modified neglect of diatomic overlap) semiempirical molecular orbital calculations

1977 ◽  
pp. 728-730 ◽  
Author(s):  
Michael J. S. Dewar ◽  
George P. Ford ◽  
Henry S. Rzepa
Keyword(s):  
Molecular Orbital ◽  
Ring Opening ◽  
Molecular Orbital Calculations ◽  
Cis And Trans ◽  
Semiempirical Molecular Orbital

Preparation of Bicyclic Herbicide Precursors by Intramolecular Stork-Danheiser Kinetic Alkylation Reactions of Methyl 1-(Haloalkyl)-3-methoxy-5-oxocyclohex-3-ene-1-carboxylate Derivatives

1992 ◽  
Vol 45 (4) ◽  
pp. 759 ◽  
Author(s):  
AJ Liepa ◽  
AJ Liepa ◽  
JS Wilkie ◽  
JS Wilkie ◽  
DA Winkler ◽  
...  
Keyword(s):  
Acid Hydrolysis ◽  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Lithium Diisopropylamide ◽  
Reductive Alkylation ◽  
Ring Fusion ◽  
Relative Stereochemistry ◽  
Alkylation Reactions ◽  
Cis And Trans ◽  
Semiempirical Molecular Orbital

Reductive alkylation of methyl 3,5-dimethoxybenzoate with the dibromoalkane and the bromochloroalkane derivatives (4a-d) and (4e-g) afforded, after acid hydrolysis, the corresponding methyl 1-( haloalkyl )-3-methoxy-5-oxocyclohex-3-ene-1-carboxylate derivatives (6a-g). Reaction of (6a-c) with lithium diisopropylamide afforded methyl 3-methoxy-5-oxobicyclo[4.2.0]oct-3-ene- 1-carboxylate (2a), methyl 5-methoxy-7-oxo-1,2,3,4,7,7a-hexahydro-3aH-indene-3a-carboxylate (2b) and methyl 6-methoxy-8-oxo-1,3,4,5,8,8a-hexahydronaphtha1ene-4a(2 H)- carboxylate (2c), respectively. Compounds (2b) and (2c) were also obtained from the reaction of (6f) and (6g) with lithium diisopropylamide . Compounds (2a) and (2b) were each obtained as a single bridgehead isomer, the relative stereochemistry of ring fusion of which was assigned as cis on the basis of semiempirical molecular orbital calculations. Compound (2c) was obtained as a mixture of cis-and trans-fused bridgehead isomers. The ester (2b) was converted into the herbicide methyl 5,7-dioxo-6-[1-[(prop-2-enyloxy) imino ] butyl]octahydro-3aH-indene-3a-carboxylate (3a).

Conformational analysis of aminovinylpyrazine by semiempirical molecular orbital calculations

1997 ◽  
Vol 33 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Hisayoshi Shiozaki ◽  
Atsushi Oshida ◽  
Dongfeng Hou ◽  
Masaru Matsuoka
Keyword(s):  
Conformational Analysis ◽  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Semiempirical Molecular Orbital
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