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2- phosphino alcohols

Asymmetric Synthesis of a-Phosphino Ketones and 2-Phosphino Alcohols... [Pg.22]

In addition to the results described, enantioselective access to 2-phosphino alcohols could be accomplished, too [71]. Starting from a borane-protected a-phosphino aldehyde hydrazone 91 as the key intermediate and available by two different approaches, the enantioselective synthesis of the desired 2-phosphino alcohols 93 could be accomplished. Thus, the electrophilic phosphinylation of aldehyde hydrazones 90 (via route I with the chlorodiphenylphosphine-borane adduct or via route II with chlorophosphines and subsequent phosphorus-boron bond formation) and the alkylation of phosphino acetaldehyde-SAMP hydrazones 92 (route III) was carried out (Scheme 1.1.26). [Pg.23]

An alternative access was achieved by alkylation of the a-diphenylphosphino acetaldehyde SAMP hydrazone 95, yielding the hydrazone products 96 in good yields (60-63%) and good diastereomeric excesses (die = 68-71%) as EjZ mixtures, from which the major diastereomer was separated and purified by preparative HPLC. Ozonolysis and in-situ reduction with the borane-dimethyl sulfide complex of the aldehydes generated gave the air-stable borane-protected 2-diphenylphosphino alcohols 97 in good yields (67-83%). Reaction with DABCO afforded the unprotected 2-phosphino alcohols 98 in very good yields (85-91%) and excellent enantiomeric excesses (ee > 96%) (Scheme 1.1.27). [Pg.24]

Scheme 1.1.26 General synthetic routes to a-phosphino alcohols. Scheme 1.1.26 General synthetic routes to a-phosphino alcohols.
The reactions of the OH group of the enantiomerically pure cis- or trans-phosphino-alcohol (98) with atropisomeric chlorophosphites have given a series of chiral phosphinocycloalkylphosphito ligands, e.g., (99). ... [Pg.12]

Metallated phosphine boranes 71 were used for regioselective ring opening of propene and styrene oxides to yield phosphino alcohols 86, which were condensed with bisphenol phosphochloridite to yield compounds 87. [Pg.209]

The ionic P-P bond polarization renders P-phosphino-NHPs highly active reactants for various metathesis and addition reactions at exceedingly mild conditions. Metathesis is observed in reactions with alcohols, chloroalkanes, and complex transition metal halides (Schemes 11 and 12) [39, 73], Of particular interest are the reactions with chlorotrimethylstannane which yield equilibria that are driven by a subtle balance of P-X bond strengths to yield either diphosphines or P-chloro-NHPs as preferred product (Scheme 11). Chlorotrimethylsilane does not react with... [Pg.89]

Formation, transamination, and mutual transitions of aminomethyl derivatives of phosphines, representing nucleophilic substitution at the carbon atom in the P—C—O(N) fragment, take place under milder conditions than similar reactions of alcohols and amines. The reason is likely the participation of a phosphino group in intramolecular interactions (86MI1). [Pg.79]

Nonmetallic systems (Chapter 11) are efficient for catalytic reduction and are complementary to the metallic catalytic methods. For example lithium aluminium hydride, sodium borohydride and borane-tetrahydrofuran have been modified with enantiomerically pure ligands161. Among those catalysts, the chirally modified boron complexes have received increased interest. Several ligands, such as amino alcohols[7], phosphino alcohols18 91 and hydroxysulfoximines[10], com-plexed with the borane, have been found to be selective reducing agents. [Pg.116]

The synthesis of dendritic carbosilanes functionalized with various diphenylphosphino carboxylic acid ester endgroups has also been reported by the Van Koten group in collaboration with Vogt et al. [40,41], The coupling of carbosilane supports containing benzylic alcohol moieties with phos-phinoxy carboxylic acid chlorides resulted in the formation of Go and Gi phosphine oxides, which subsequently were converted into the phosphino... [Pg.13]

Chiral chelating ligands that contain only one phosphine and another donor atom have been successful in recent years. A readily synthesized example is the phosphino-oxazoline ligand 87 shown in Scheme 31. These types of ligand can be prepared in two steps from an amino alcohol, a substituted benzonitrile and either a electrophillic or nucleophilic phosphorus reagent. They have been used in a number of asymmetric reactions. [Pg.41]

Tridentate salen ligands (10) derived from 1 have given excellent results in the enantiocontrol of the hetero Diels-Alder addition reaction of dienes with aldehydes (eq 7) and in the asymmetric additions of TMS-azide to mc5o-epoxide and trimethylsilyl cyanide to benzaldehyde (up to 85% ee). Phosphino-oxazolines derived from 1 have been employed for the asymmetric control of palladium-catalyzed allylic substitution reactions products of 70-90% ee were obtained. Photolysis of crystalline adducts of enantiomerically pure 1 with prochiral alcohols results in asymmetric inductions of up to 79% in a rare example of a solid-state enantioselective reaction. ... [Pg.29]

According to eq. (2), ally alcohol is converted to 1,4-butanediol by rhodium-catalyzed hydroformylation and hydrogenation of 2-hydroxytetrahydrofuran [51, 52]. In 1990 ARCO launched a production plant based on the technology developed by Kuraray with a 30000 tons/year 1,4-butanediol capacity [53], Presumably the rhodium catalyst is modified by the diphosphine DPPB (1,4-bis(diphenyl-phosphino)butane) [54]. [Pg.40]


See other pages where 2- phosphino alcohols is mentioned: [Pg.22]    [Pg.25]    [Pg.13]    [Pg.7]    [Pg.10]    [Pg.186]    [Pg.74]    [Pg.226]    [Pg.73]    [Pg.88]    [Pg.269]    [Pg.362]    [Pg.1169]    [Pg.117]    [Pg.204]    [Pg.395]    [Pg.18]    [Pg.13]    [Pg.35]    [Pg.105]    [Pg.312]    [Pg.38]    [Pg.40]    [Pg.234]    [Pg.272]    [Pg.276]    [Pg.13]    [Pg.26]    [Pg.3]    [Pg.22]    [Pg.27]    [Pg.8]    [Pg.17]    [Pg.126]   
See also in sourсe #XX -- [ Pg.22 ]




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