Unravelling the Mechanism of Non-photoactivated [2+2] Cycloaddition Reactions: Relevance of Orbital Interactions and Zwitterionic Intermediates

2017 ◽  
Vol 2 (3) ◽  
pp. 1089-1093 ◽  
Author(s):  
Enrique M. Arpa ◽  
Fernando Aguilar-Galindo ◽  
Sergio Díaz-Tendero
Keyword(s):  
Cycloaddition Reactions ◽  
Orbital Interactions

Regio- and stereoselectivity of [2+3]cycloaddition of nitroethene to (Z)-N-aryl-C-phenylnitrones

2009 ◽  
Vol 74 (9) ◽  
pp. 1341-1349 ◽  
Author(s):  
Radomir Jasiński
Keyword(s):  
Cycloaddition Reactions ◽  
Orbital Interactions ◽  
Steric Factors

The cycloaddition reactions of nitroethene to (Z)-N-aryl-C-phenylnitrones lead to mixtures of stereoisomeric cis- and trans-2-aryl-4-nitro-3-phenylisoxazolidines. Regioselectivity of these reactions is determined by the character of nucleophile–electrophile interactions, while stereoselectivity is determined by the steric factors and the character of secondary orbital interactions.

1,3-Dipolar cycloaddition reactions of monocyclic aziridines with dimethyl 1-cyclobutene-1,2-dicarboxylate

1994 ◽  
Vol 72 (10) ◽  
pp. 2108-2117 ◽  
Author(s):  
Kiyoshi Matsumoto ◽  
Hirokazu Iida ◽  
Takane Uchida ◽  
Yoshimi Yabe ◽  
Akikazu Kakehi ◽  
...  
Keyword(s):  
Ring Opening ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Thermally Induced ◽  
X Ray ◽  
Orbital Interactions ◽  
Dipole Interactions

The thermally induced [2 + 3] cycloadditions of certain monocyclic aziridines to dimethyl 1-cyclobutene-1,2-dicarboxylate are described. The structures of the resulting bicyclic adducts were established unambiguously by X-ray analyses. The stereochemistries of the [2 + 3] adducts were interpreted in terms of dipole–dipole interactions and secondary orbital interactions. In certain cases an initial thermal conrotatory ring opening of the cyclobutene to 2,3-di(methoxycarbonyl)-1,3-butadiene precedes the [2 + 3] cycloaddition, affording the unexpected pyrrolidine adducts 12a and 12b. The structures and stereochemistries of the latter established by X-ray analysis strongly suggest that secondary orbital interactions between the phenyl and ester groups control and stereochemistry of the reactions.

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