Cyanide as a Powerful Catalyst for Facile Preparation of 2-Substituted Benzoxazoles<i>via</i>Aerobic Oxidation
作者:Yeon Ho Cho、Chun-Young Lee、Deok-Chan Ha、Cheol-Hong Cheon
DOI:10.1002/adsc.201200684
日期:2012.11.12
synthesis of 2-substituted benzoxazoles from Schiff bases via aerobic oxidation has been developed. The products from various Schiff bases were obtained in high yields in an open flask under ambient conditions without other external oxidants. We have also developed a simple one-step protocol for the synthesis of benzoxazoles from aminophenol and the corresponding aldehydes in the presence of cyanide without
Enantioselective Strecker and Allylation Reactions with Aldimines Catalyzed by Chiral Oxazaborolidinium Ions
作者:Ki-Tae Kang、Sang Hyun Park、Do Hyun Ryu
DOI:10.1021/acs.orglett.9b02280
日期:2019.9.6
Chiral oxazaborolidiniumion (COBI)-catalyzed enantioselective nucleophilic addition reactions of aldimines using tributyltin cyanide and allyltributylstannane have been developed. Various α-aminonitriles and homoallylic amines were synthesized in high yield (up to 98%) with high to excellent enantioselectivity (up to 99% ee). A rational mechanistic model for the complex of COBI and aldimine is provided
The asymmetric Povarov reaction with α‐alkyl styrenes as dienophiles was catalyzed by an N,N′‐dioxide L4–Sc(OTf)3 complex. Enantiopure tetrahydroquinoline derivatives with a quaternary stereocenter at the C4 position were synthesized for the first time. A wide variety of α‐alkyl styrenes and N‐aryl aldimines were tolerated in the reaction, to give excellent diastereo‐ (up to 99:1 d.r.) and enantioselectivities
An enantioselective bisvinylogous Mannich reaction of silyl ketene acetal with aldimines has been realized by using a chiral N,N′‐dioxide/Tm(OTf)3 complex as catalyst, providing an effective method to synthesize chiral ζ‐amino‐α,β,γ,δ‐unsaturated carbonyl compounds.
A direct highly diastereo- and enantioselective asymmetricvinylogousMannich-type (AVM) reaction of aldimines with nonactivated natural α-angelica lactone has been successfully developed. It was demonstrated that the nonactivated natural α-angelica lactone is a useful vinylogous nucleophile to give the chiral δ-amino γ,γ-disubstituted butenolide carbonyl derivatives. The N,N′-dioxide L2–ScIII complex