Intramolecular Michael Addition of N- and O-Centred Nucleophiles to Tethered Acrylates. The Role of Double-Bond Geometry in Controlling the Diastereo- selectivity of Cyclizations Leading to 2,6-Disubstituted Tetrahydropyrans and Piperidines.
Rhodium-Catalyzed Asymmetric Conjugate Alkynylation/Aldol Cyclization Cascade for the Formation of α-Propargyl-β-hydroxyketones
作者:Ken-Loon Choo、Mark Lautens
DOI:10.1021/acs.orglett.8b00153
日期:2018.3.2
A rhodium-catalyzedconjugatealkynylation/aldol cyclization cascade was developed. Densely functionalized cyclic α-propargyl-β-hydroxyketones were synthesized with simultaneous formation of a C(sp)–C(sp3) bond, a C(sp3)–C(sp3) bond, as well as three new contiguous stereocenters. The transformation was achieved with excellent enantio- and diastereoselectivities using BINAP as the ligand. The synthetic
Borane-Mediated Aldol Cycloreduction of Monoenone Monoketones: Diastereoselective Formation of Quaternary Centers
作者:Ryan R. Huddleston、David F. Cauble、Michael J. Krische
DOI:10.1021/jo020629f
日期:2003.1.1
Exposure of monoenone monoketones to catecholborane in THF at ambient temperature results in tandem 1,4-reduction-aldol cyclization. For aromatic and heteroaromatic enones, six-memberedcyclic aldol products are formed in excellent yield with high levels of syn diastereoselectivity. Five-membered ring formation proceeds less readily, but the yield of cyclized product is improved through introduction
A remarkable proline-catalyzed method for the construction of biologically interesting oxygen-bridged tricyclic ketal skeletons was uncovered by starting from a variety of readily available cyclic 1,3-diketones and either 1,4- or 1,5-dicarbonyl substrates. The approach, which mimics a biosynthetic Knoevenagelcondensation/[4+2] cycloaddition sequence, establishes a viable synthetic strategy for the
[EN] HETEROCYCLYLPYRI (MI) DINYLPYRAZOLE AS FUNGICIDALS<br/>[FR] HÉTÉROCYCLYLPYRIDINYLPYRAZOLE ET HÉTÉROCYCLYLPYRIMIDINYLPYRAZOLE UTILISÉS COMME FONGICIDES
申请人:BAYER IP GMBH
公开号:WO2013050437A1
公开(公告)日:2013-04-11
Heterocyclylpyri(mi)dinylpyrazole of the formula (I) in which R1 to R5, X1, U, Q, W, Y, n, a, b have the meanings given in the description, and agrochemically active salts, to their use and to methods and compositions for controlling phytopathogenic harmful fungi in and/or on plants or in and/or on seed of plants and for reducing mycotoxins in plants and parts of the plants, to processes for preparing such compounds and compositions and treated seed and also to their use for controlling phytopathogenic harmful fungi in agriculture, horticulture, forestry, in animal husbandry, in the protection of materials, in the domestic and hygiene field and for the reduction of mycotoxins in plants and parts of the plants.
A New Chemoselective Base-Mediated Protection/Deprotection Method for Aldehydes
作者:Darren J. Dixon、Mark S. Scott、Chris A. Luckhurst
DOI:10.1055/s-2003-42470
日期:——
wide range of aldehydes was efficiently protected as pyrrole carbinol derivatives by direct addition of lithium pyrrolate in THF at -78 °C. The protection is chemoselective towards aldehydes over ketones and the O-lithiated, O-protonated or O-silylated carbinols may be used to block the aldehyde from nucleophilic and basic reagents at low temperatures. Mild, basic deprotection using DBU, NaOMe or TBAF