Diastereoselectivity in the Reaction of RCH
2
C[CH
2
P (Ar)(Lr)]
3
with Electrophiles: Enhancement of Diastereoselective Control by η
3
‐Coordination in {RCH
2
C[CH
2
P(Ar)(Li)
3
}Mo(Co)
3
摘要:
AbstractFollowing a procedure developed for H3CC[CH2P(Ph)2]3 (1a) as the starting compound, various tripod ligands RCH2C[CH2P(Ar)2]3 (1) have been transformed into the trilithiotriphosphides RCH2C[CH2P(Ar)(Li)]3 with various electrophiles R′ — Hal leads to the two diastereomers of RCH2C[CH2P‐(Ar)(R)]3 (6) with an (RRR/SSS : RRS/SSR) ratio close to the statistical value of 1:3, except when ArPh and R′Bzl, where the RRS/SSR diastereomer is obtained almost exclusively. In contrast, the reaction of [RCH2C[CH2P(Ar)(Li)[3]‐Mo(CO)3 (4) with electrophiles R′ — Hal tends to favour the formation of the homochiral RRR/SSS diastereomers. The triphosphide coordination compounds 4 are available by two different routes: either the complexes (RCH2C[CH2P‐(Ar)(H)]3Mo(CO)3, obtained from 2 and (CH3CN)3Mo(CO)3, are deprotonated by MeLi, or the trilithiotriphosphides RCH2C[CH2P(Ar)(Li)]3 are reacted with (CH3CN)3Mo(CO)3 to produce 4 in high yields. The ration in which the two diastereomeric forms of 5 are obtained depends on the nature of the electrophile: the greatest diastereomeric discrimination is obtained for ArPh, RPh, R′Bzl, where the homochiral relative to the RRS/SSR pair. Two‐dimensional NMR spectra and simulations of one‐dimensional spectra are used to ascertain the diastereomeric excess in each case. X‐ray analyses of three compounds of type 5 (5d, ArPh, RH, R′Ph, R′Bzl) indicate the remarkable conformational stability of the tripod metal scaffolding, with the conformations observed for these three compounds in three different solid‐state environments being closely similar, even with respect to the torsional arrangement of the phosphorus‐bound benzyl groups.
The reaction of 1,1,1-tris(chlormethyl)ethane H3CC(CH2Cl)3 with Ar2PH in DMSO as the solvent using KOH/H2O as the base gives good yields of tripod ligands H3CC(CH2PAr2)3, 2. Using Ph2PH as the phosphine component, it is shown that the chloride substituents of H3CC(CH2Cl)3 are exchanged in sequence by the formation of H3CC(CH2Cl)2(CH2PPh2), 1a, and H3CC(CH2Cl)(CH2PPh2)2, 1b, respectively. The product
tailored tridentate ligand enabled the synthesis of a molecular ruthenium‐triphos catalyst, eliminating dimerization as the major deactivation pathway. The novel catalyst design showed strongly increased performance and facilitated the hydrogenation of highly challenging lactam substrates with unprecedented activity and selectivity.
METHOD FOR PRODUCING ALCOHOL BY HYDROGENATING LACTONE AND CARBOXYLIC ACID ESTER IN LIQUID PHASE
申请人:Maeda Hirofumi
公开号:US20100113842A1
公开(公告)日:2010-05-06
Disclosed is a method for producing an alcohol from a lactone or a carboxylic acid ester, which enables to produce an alcohol from a lactone or a carboxylic acid ester under relatively mild conditions with high yield and high catalytic efficiency. This method also enables to produce an optically active alcohol from an optically active lactone or an optically active carboxylic acid ester. Specifically disclosed is a method for producing an alcohol by hydrogen reducing a lactone or a carboxylic acid ester in the presence of a catalyst containing ruthenium and a phosphine compound represented by the following general formula (1):
wherein R
1
represents a spacer; R
2
, R
3
, R
4
, R
5
, R
6
and R
7
independently represent a hydrogen atom, an alkyl group having 1-12 carbon atoms, an aryl group or a heterocyclic group; and R
8
, R
9
, R
10
, R
11
, R
12
and R
13
independently represent an alkyl group having 1-12 carbon atoms, an aryl group or a heterocyclic group.