Cycloaddition catalytic asymmetric

Nickel(O) complexes catalyse [2+2+2] cycloaddition. Catalytic asymmetric synthesis of isoquinoline derivative 134 is possible based on enantiotopic group-selective formation of the nickelacyclopentadiene 133 from 132 using the Ni(0) complex coordinated by a chiral ligand under acetylene atmosphere [56]. 

Catalytic asymmetric Diels-Alder reactions are presented by Hayashi, who takes as the starting point the synthetically useful breakthrough in 1979 by Koga et al. The various chiral Lewis acids which can catalyze the reaction of different dieno-philes are presented. Closely related to the Diels-Alder reaction is the [3-1-2] carbo-cyclic cycloaddition of palladium trimethylenemethane with alkenes, discovered by Trost and Chan. In the second chapter Chan provides some brief background information about this class of cycloaddition reaction, but concentrates primarily on recent advances. The part of the book dealing with carbo-cycloaddition reactions is... 

See e.g. (a) W. Cahhuthehs, Cycloaddition Reactions in Organic Synthesis, Tetrahedron Organic Chemistry Series Vol. 8 Pergamon Press Elmsford, NY 1990 (b) I. OjiMA, Catalytic Asymmetric Synthesis, VCH Publishers. Inc. New York. 1993 ... 

Dochnahl M, Fu GC (2009) Catalytic asymmetric cycloaddition of ketenes and nitroso compounds enantioselective synthesis of a-hydroxycarboxylic acid derivatives. Angew Chem Int Ed 48 2391-2393... 

This chapter focuses on some typical examples, starting with the usual cycloaddition reactions and then the catalytic asymmetric Diels-Alder reactions, hetero Diels-Alder reactions, retro Diels-Alder reactions, and intramolecular... 

Since then, optically active a-aminophosphonates have been obtained by a variety of methods including resolution, asymmetric phosphite additions to imine double bonds and sugar-based nitrones, condensation of optically active ureas with phosphites and aldehydes, catalytic asymmetric hydrogenation, and 1,3-dipolar cycloadditions. These approaches have been discussed in a comprehensive review by Dhawan and Redmore.9 More recent protocols involve electrophilic amination of homochiral dioxane acetals,10 alkylation of homochiral imines derived from pinanone11 and ketopinic acid,12 and alkylation of homochiral, bicyclic phosphonamides.13... 

Modifications to the architecture of the imidazolidinone catalyst provided the fnryl derivative (20) which proved to be a powerfnl catalyst for the catalytic asymmetric Diels-Alder cycloaddition of simple a,P-unsaturated ketones [50]. Although... 

The aza-Diels-Alder reaction is an important and versatile tool for the preparation of nitrogen-containing heterocycles present in numerous natural products and drug candidates. It involves the [4 + 2] cycloaddition of either an imine with an electron-rich diene or an azabutadiene with an electron-rich alkene (inverse electron demand). Catalytic asymmetric variants employing not only metal complexes, but also organic molecules were disclosed over the last few years. 

The initial work on the asymmetric [4-1-2] cycloaddition reactions of A -sulfinyl compounds and dienes was performed with chiral titanium catalysts, but low ee s were observed <2002TA2407, 2001TA2937, 2000TL3743>. A great improvement in the enantioselectivity for the reaction of AT-sulfinyl dienophiles 249 or 250 and acyclic diene 251 or 1,3-cyclohexadiene 252 was observed in the processes involving catalysis with Cu(ll) and Zn(ii) complexes of Evans bis(oxazolidinone) (BOX) ligands 253 and 254 <2004JOC7198> (Scheme 34). While the preparation of enantio-merically enriched hetero-Diels-Alder adduct 255 requires a stoichometric amount of chiral Lewis acid complex, a catalytic asymmetric synthesis of 44 is achieved upon the addition of TMSOTf. 

Many groups have tackled the development of catalytic asymmetric versions of nitrile oxide cycloaddition reactions using chiral Lewis acid catalysts. However, Ukaji is the first and the only chemist who has succeeded in the achievement of such processes involving nitrile oxide cycloaddition reactions. He studied reactions... 

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