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An efficient diastereo- and enantioselectiveMannich-type/cyclizationcascade reaction of α-substituted isocyanoacetates and cyclictrifluoromethyl ketimines cooperatively catalyzed by cinchonaalkaloid-derived multi-hydrogen-bonding donor squaramide and AgOAchas been investigated, affording the optically active trifluoromethyl-substitutedtetrahydroimidazo[1,5-c]quinazoline derivatives inexcellent yields (up to 99%) and good to excellent stereoselectivities(up to >15:1 dr, up to 98% ee) under mild conditions. [ABSTRACT FROM AUTHOR]

Cinchona alkaloid squaramide can effectively catalyze the asymmetric Michael addition of α-aryl isocyanoacetates to β-trifluoromethylated enones, affording the corresponding adducts with an adjacent chiral tertiary carbon center bearing a CF3 group and a quaternary carbon center in moderate to good yields along with excellent stereoselectivities. The adduct can be easily transformed into biologically attractive chiral β-trifluoromethylated pyrroline carboxylate in high yield via an isocyano group hydrolysis/cyclization/dehydration cascade reaction by treating with acid. The one-pot enantioselective Michael addition/isocyano group hydrolysis/cyclization/dehydration sequential protocol has also been investigated.

An efficient enantioselective hydrazination/cyclization cascade reaction of α-substituted isocyanoacetates to azodicarboxylates catalyzed by Cinchona alkaloid derived squaramide catalysts has been investigated, affording the optically active 1,2,4-triazolines in excellent yields (up to 99%) and good to excellent enantioselectivities (up to 97% ee) under mild conditions.

Asymmetric epoxidation of olefins by using an alpha,alpha-dimethylmorpholinone-containing chiral ketone catalyst (4) has been investigated. This ketone, which has the combined features of several previously studied catalysts, is an effective catalyst for trans- and trisubstituted olefins, and up to 97% ee has been achieved. The alpha,alpha-dimethyl group has significant impact on spiro and planar transition states.

A fructose-derived diacetate ketone has been shown to be an effective catalyst for asymmetric epoxidation. High ee values have been obtained for a variety of trans and trisubstituted olefins including electron-deficient alpha,beta-unsaturated esters as well as certain cis olefins.

Various 1,1-disubstituted terminal olefins have been investigated for asymmetric epoxidation using chiral ketone catalysts. Up to 88% ee has been achieved with a lactam ketone, and a planar transition state is likely to be a major reaction pathway.

Axially chiral BINIM-Ni(II) complexes are effective catalysts in the asymmetric 1,3-dipolar cycloaddition reactions of azomethine ylides and N-arylmaleimides to give the corresponding adducts in good yields and up to 95% enantiomeric excesses.

An L-fructose-derived ketone catalyst for asymmetric epoxidation of trans- and trisubstituted olefins was efficiently prepared from L-sorbose in five steps.

A novel and practical synthesis of heterocyclic enamines has been developed from the formal ring enlargement of cyclic ketones, which comprised the retro-Reformatsky fragmentation reaction as a key step. Under alkaline bromination conditions, the Reformatsky adducts derived from five- to seven-membered cyclic ketones underwent efficiently a direct retro-Reformatsky fragmentation, followed by spontaneous alpha,alpha-dibromination, to produce alpha,alpha,omega-tribromo-beta-ketoester compounds in a one-pot reaction. Highly regioselective reduction of alpha,alpha,omega-tribromo-beta-ketoesters with Cu-Zn alloy under mild conditions afforded omega-bromo-beta-ketoesters in good to excellent yields. Treatment of omega-bromo-beta-ketoesters with sodium azide followed by intramolecular aza-Wittig reaction or catalytic hydrogenation furnished heterocyclic secondary enamines, while a straightforward cyclocondensation of omega-bromo-beta-ketoesters with amines led to the formation of heterocyclic tertiary enamines.