An Amino Alcohol Ligand for Highly Enantioselective Addition of Organozinc Reagents to Aldehydes: Serendipity Rules
作者:William A. Nugent
DOI:10.1021/ol0259488
日期:2002.6.1
bis(2-bromoethyl) ether. Subsequent hydrogenation over 5% Rh on alumina in the presence of morpholine unexpectedly stops at the hexahydro derivative 4. Amino alcohol 4 promotes the enantioselectiveaddition of diethylzinc to aldehydes at room temperature in up to 99% enantiomeric excess.
Third-Generation Amino Acid Furanoside-Based Ligands from <scp>d</scp>
-Mannose for the Asymmetric Transfer Hydrogenation of Ketones: Catalysts with an Exceptionally Wide Substrate Scope
A modular ligand library of α‐amino acid hydroxyamides and thioamides was prepared from 10 different N‐tert‐butyloxycarbonyl‐protected α‐amino acids and three different amino alcohols derived from 2,3‐O‐isopropylidene‐α‐d‐mannofuranoside. The ligand library was evaluated in the half‐sandwich ruthenium‐ and rhodium‐catalyzed asymmetric transfer hydrogenation of a wide array of ketone substrates, including
The enantioselectiveaddition of organozincreagents to aromatic and aliphatic aldehydes 1 gives secondary alcohols 2 with excellent enantioselectivities in high yields through the catalytic use of (R)-3,3′-bis(diphenylphosphinoyl)-BINOL (3) or (R)-3,3′-bis(diphenylthiophosphinoyl)-BINOL (4) without Ti(IV) complexes. The coordination of the O or S atom of a (thio)phosphinoyl group bearing a BINOL backbone
A highlyenantioselective dialkylzinc (R22Zn) addition to a series of aromatic, aliphatic, and heteroaromatic aldehydes (5) was developed based on conjugate Lewis acid−Lewis base catalysis. Bifunctional BINOL ligands bearing phosphine oxides [P(O)R2] (7), phosphonates [P(O)(OR)2] (8 and 9), or phosphoramides [P(O)(NR2)2] (10) at the 3,3‘-positions were prepared by using a phospho-Fries rearrangement
Highly enantioselective dialkylzinc addition to a series of aldehydes was developed based on chiral Zn(II)-BINOLate catalysts bearing phosphonates [P(=O)(OR) 2 ] and phosphoramides [P(=O)(NMe 2 ) 2 ] at the 3,3'-positions. The reactions proceeded smoothly and showed reductions in the amounts of both catalysts and dialkylzinc reagents to be loaded.