Highly Enantioselective Azadiene Diels−Alder Reactions Catalyzed by Chiral N-Heterocyclic Carbenes
摘要:
Highly enantioselective, N-heterocyclic carbene (NHC)-catalyzed aza-Diels-Alder reactions are described. A novel chiral triazolium salt based on the cis-1,2-aminoindanol platform serves as an efficient precatalyst for the NHC-catalyzed redox generation of enolate dienophiles that undergo LUMOdiene-controlled Diels-Alder reactions with N-sulfonyl-alpha,beta-unsaturated imines in good yields and with exceptional diastereo- and enantioselectivities (>99% ee). In contrast to uncatalyzed variants, this organocatalytic process proceeds at room temperature without stoichiometric reagents, producing synthetically valuable, enantiomerically pure cis-3,4-disubstituted dihydropyridinone products.
Heterocyclic triazolylethyl ether compounds and their use as pesticides
申请人:Imperial Chemical Industries Limited
公开号:US04315016A1
公开(公告)日:1982-02-09
Fungicidal compounds of the formula: ##STR1## wherein R.sub.3 is hydrogen, R.sub.4 is phenyl optionally substituted with one halogen, and R.sub.5 is alkyl having up to 5 carbon atoms, alkenyl having up to 5 carbon atoms, alkynyl having up to 5 carbon atoms or monochlorophenoxymethyl or R.sub.5 is benzyl optionally ring substituted with up to three substituents selected from the class consisting of halogen, alkyl having up to 4 carbon atoms and alkoxy having up to 4 carbon atoms, or a fungicidal acid salt of such a compound.
This invention is to provide a process for preparing 1-amino-1,2,3-triazole represented by formula (III): ##STR1## comprising cyclizing glyoxal bishydrazone represented by formula (I): ##STR2## by reaction with an aqueous hydrogen peroxide solution in the presence of a catalytic amount of a transition metal oxide represented by formula (II): M.sub.m O.sub.n wherein M represents a transition metal atom; and m and n, which may be the same or different, each represent an integer of 1 to 5.