reactions involving nickel‐catalyzed additions of (hetero)arylboronic acids to alkynes, followed by cyclization of the alkenylnickel intermediates onto tethered acyclic ketones to give chiral tertiary‐alcohol‐containing products in high enantioselectivities, are described. The reversible E/Z isomerization of the alkenylnickel intermediates enables overall anti‐arylmetallative cyclization to occur. The ring
Palladium/monophosphine complexes catalyze trans-selective arylative, alkenylative, and alkylativecyclization reactions of alkynals and alkynones with organoboronic reagents. These reactions afford six-membered allylic alcohols with endo-tri- or tetrasubstituted olefin groups and/or five-membered counterparts with exo olefin groups. The ratios of these products are dramatically affected by alkyne
Palladium(II)-Catalyzed Asymmetric Tandem Cyclization of 2-Aminoaryl Alkynones: An Approach to Chiral 1,2,3,4-Tetrahydro-β-carbolines
作者:Junjie Chen、Xiuling Han、Xiyan Lu
DOI:10.1021/acs.orglett.8b03247
日期:2018.12.7
A Pd(OAc)2-catalyzed asymmetric cyclization of 2-aminoaryl alkynones involving an intramolecular trans-aminopalladation of alkyne and 1,2-addition to the carbonyl group tandem processes was developed. This strategy represents the first example using palladium as the catalyst and 2-alkynylaniline derivatives as the starting material to allow facile access to chiral 1,2,3,4-tetrahydro-β-carbolines in
A rare example of cyclization with 5-alkynones, which possess non-polar alkynyl and less electrophilic polar keto carbonyl groups, was demonstrated. The key to promoting carbene/alkyne metathesis followed by alkylidenation with pendant CO double bonds was the Schrock-type nucleophilic reactivity of the generated chromium carbene equivalents from readily available diiodomethanes and CrCl2 by simple
Palladium(0)‐Catalyzed
<i>Anti</i>
‐Selective Addition‐Cyclizations of Alkynyl Electrophiles
作者:Hirokazu Tsukamoto、Kazuya Ito、Tatsuhiko Ueno、Mitsugu Shiraishi、Yoshinori Kondo、Takayuki Doi
DOI:10.1002/chem.202203068
日期:2023.1.27
Palladium(0)/monophosphine complexes catalyze anti-selective arylative cyclizations of alkynyl electrophiles with organometallic reagents. Remarkably, the regioselectivity in the cyclization of conjugated diyne-aldehydes can be controlled by a choice of the phosphine ligand, with triphenylphosphine and tricyclohexylphosphine leading to the exclusive formation of 2-alkylidene-cyclopentanol and 2-cyclohexen-1-ol