Reactivity regioselectivity

Keywords reactivity, regioselectivity, diastereoselectivity, diastereofacial selectivity, Lewis acids... 

Discussions about reactivity, regioselectivity and stereoselectivity are mostly based on a more qualitative application of equation 15. To that aim, the following general considerations given by Fleming51 and Houk52 can be used to evaluate the influence of substituents on the reacting it systems ... 

Friedrichsen and co-workers (135), along with Padwa, has utilized the carbonyl ylide cycloaddition to generate reactive furan moieties that can be further used in inter- or intramolecular Diels-Alder reactions to prepare aza- and carbocyclic compounds. Friedrichsen conducted a number of synthetic and theoretical studies on the reactivity, regioselectivity, and stereoselectivity of substituted furan formation and subsequent Diels-Alder reaction (Scheme 4.69). 

Molecular orbital models are valuable aids in understanding the reactivity, regioselectivity, and stereospecificity phenomena exhibited by cycloaddition reactions and in predicting reactivity and product identities for addend pairs. Symmetry-energy correlation diagrams indicate that the 1,3-dipolar cyclo-... 

A I Cycloaddition reactions are among the most powerful reactions available to the organic chemist. The ability to simultaneously form and break several bonds, with a wide variety of atomic substitution patterns, and often with a high degree of stereocontrol, has made cycloaddition reactions the subject of intense study. The productive interplay between theory and experiment has resulted in sophisticated models which often allow one to predict reactivity, regioselectivity, and stereoselectivity for given cycloaddition partners. 

Frequently, Pd(PPh3)4 (or another Pd" complex) is used as a catalyst for the displacement of aUyUc acetates or halides by nucleophiles. A general catalytic cycle is depicted in Scheme 30. If chloride ions are present, no ( 7r-allyl)PdL2 forms. Instead, a ((( -allyl)PdL2Cl intermediate is formed. Thus, different precursors (such as aUylic chlorides or aUylic acetates) or different reaction conditions can lead to different reactivities, regioselectivities, and enantioselectivities. 

Relative Reactivity, Regioselectivity, Stereoselectivity, and Transition Structures... 

Keywords FuUerenes (higher fullerenes). Chirality, Stereo descriptors. Reactivity, Regioselectivity. 

Palladium-catalyzed aUyUc alkylation of allyl dienol carbonates Reactivity, regioselectivity, enantioselectivity, and synthetic applications, particularly, straightforward access to di-, tri-, and tetrasubstituted furans and pyrroles 13SL2350. 

Rhodium complexes provide some of the most attractive catalysts for carbon manipulation with high reactivity, regioselectivity, scope, and functional group tolerance. In particular, rhodium complexes have displayed potential for the synthesis of various heterocyclic and carbocyclic compounds through the C—H bond activation reactions. Rhodium complexes have been shown to catalyze sp C—H bond insertion into several pi bonds including alkenes, alkynes, aldehydes, and imines. ... 

The reactivity, regioselectivity and stereoselectivity of [3+2] cycloadditions of oxazoline 7V-oxides and a,P-unsaturated esters or nitroalkenes can be rationalized in terms of the FMO theory. The reactions are HOMO-dipole controlled and the preferred ewi/o-selectivity in those cycloadditions can be rationalized by stabilizing secondary orbital interactions only present in the en[Pg.105]

Kropf, H. and Reichwaldt, R., Photooxygenation of phenyl-substituted propenes, but-2-enes and pent-2-enes reactivity, regioselectivity and stereoselectivity, /. Chem. Res. (S), 412,1987. 

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