A catalytic synthetic route to highly functionalized chiral cyclopropane derivatives was developed by Michael-initiated cyclopropanation of α-substituted acroleins with aryl- and alkyl diazoacetates. In the presence (S)-oxazaborolidinium cation 1b as a catalyst, reaction proceeded in high yield (up 93%) excellent diastereoselectivity 98% de) enantioselectivity 95% ee).

Breaking kamp: A catalytic route toward chiral α-alkyl-β-ketoesters using the title reaction of α-alkyl diazoester with aldehydes has been developed (see scheme). The proceeds high to excellent enantioselectivities and this methodology was applied a concise two-step synthesis natural pheromone sitophilate. Roskamp reaction,1 Lewis acid catalyzed alkyl diazoesters aldehydes, is powerful useful synthetic method construct β-keto carbonyl compounds, which have utilized in products2 (Scheme 1)....

This paper describes a catalytic enantioselective route to synthesize functionalized all-carbon quaternary acyclic systems via boron Lewis acid-promoted formal C-C insertion of diazoesters into aryl-CHO bonds. In the presence chiral (S)-oxazaborolidinium cation 1d as catalyst, reaction proceeded in good yield (up 83%) with regioselectivity 88:12) and excellent enantioselectivity 99% ee). The synthetic potential this method was illustrated by conversion products both α- β-amino esters.

A catalytic route to highly functionalized chiral 2-pyrazolines by an asymmetric 1,3-dipolar cycloaddition reaction of ethyl diazoacetate with α-substituted and α,β-disubstituted acroleins has been developed; in the presence (S)-oxazaborolidinium ion 1 as catalyst, proceeded high excellent enantioselectivities (up 99% ee).

A cationic oxazaborolidinium-catalyzed asymmetric Mukaiyama aldol reaction of (1-methoxy-2-methyl-propenyloxy)-trimethylsilane with various aldehydes including α,β-disubstituted acroleins has been developed in high yields and enantioselectivities. The synthetic utility this methodology was demonstrated the first short synthesis naturally occurring inthomycin C enantiopurity.

The catalytic asymmetric inverse-electron-demand oxa-Diels-Alder (IODA) reaction is a highly effective synthetic method for creating enantioenriched six-membered oxygen-containing heterocycles. Despite significant effort in this area, simple α,β-unsaturated aldehydes/ketones and nonpolarized alkenes are seldom utilized as substrates due to their low reactivity difficulties achieving enantiocontrol. This report describes an intermolecular IODA between α-bromoacroleins neutral that catalyzed...

A metal-free route to 1,4-disubstituted and 1,4,5-trisubstituted formyl triazoles was developed. One 1,2,3-triazole containing diastereotopic protons identified.

Ein katalytischer Zugang zu chiralen α-Alkyl-β-ketoestern besteht in der Umsetzung von α-Alkyldiazoestern mit Aldehyden (siehe Schema). Die Titelreaktion ergibt hohe bis ausgezeichnete Enantioselektivitäten und bewährt sich einer zweistufigen Synthese des natürlichen Pheromons Sitophilat. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by the authors....

Abstract A catalytic enantioselective formal [2+2] cycloaddition between α‐halo acroleins and electronically diverse arylalkenes is described. In the presence of (S)‐oxazaborolidinium cation as catalyst, densely functionalized cyclobutanes containing two vicinal tetrasubstituted stereocenters were produced in high yields diastereoselectivities with excellent enantioselectivities. Mechanistic studies revealed that cis isomer could be transformed into trans via an enantiocontrolled process....

Abstract Functional Schiff base chelating groups (PCA) were covalently grafted onto the surface of magnetic graphene oxide (GO‐Fe 3 O 4 ) via a facile silanization reaction under mild condition. The obtained GO‐Fe ‐PCA was further chelated with CuCl 2 as an efficient, robust, and recyclable semi‐heterogeneous catalyst ‐CuCl for one‐pot three‐component KA coupling ketones, amines, alkynes. It exhibited environmentally benign, excellent separation performance, higher catalytic activity than...

In this Letter, a catalytic diastereoselective hetero-Diels-Alder reaction of α-haloacroleins with less polarized alkenes was developed, and the resulting 3,4-dihydropyrans were produced in high yields broad substate scope. Mechanism studies showed that 3,4-dihydropyran from ring expansion cyclobutane, which generated contraction initially formed unstable conformer.

Abstract A catalytic enantioselective formal [2+2] cycloaddition between α‐halo acroleins and electronically diverse arylalkenes is described. In the presence of (S)‐oxazaborolidinium cation as catalyst, densely functionalized cyclobutanes containing two vicinal tetrasubstituted stereocenters were produced in high yields diastereoselectivities with excellent enantioselectivities. Mechanistic studies revealed that cis isomer could be transformed into trans via an enantiocontrolled process....

Abstract The first example of a highly enantioselective catalytic C—C insertion diazoesters into aldehydes affords functionalized acyclic all‐carbon α‐quaternary aldehydes.

Abstract An efficient and enantioselective Mukaiyama aldol reaction between ketene silyl acetals a variety of aldehydes is developed using OAB as catalyst.

Abstract A catalytic route toward chiral α‐alkyl‐β‐ketoesters using the title reaction of α‐alkyl diazoester with aldehydes is developed.

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