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Reduction of thiol esters

Aldehyde synthesis through reduction of thiol esters with EtsSiH in the presence of Pd/C catalyst. [Pg.249]

Reduction of thiol esters. Thiol esters, R COSR2, are reduced to primary alcohols, R CH2OH, in high yield by NaBH4 in C2H5OH without reduction of nitrile, ester, and amide substituents.7... [Pg.244]

Table 7 The Reduction of Thiol Esters RCOSR to Aldehydes RCHO by Deactivated Raney Nickel... Table 7 The Reduction of Thiol Esters RCOSR to Aldehydes RCHO by Deactivated Raney Nickel...
Reduction of Thiol Esters with Smb and Synthetic Application... [Pg.87]

The reduction of thiol esters to aldehydes using Raney nickel was reported to proceed in 70-80% ethanol under reflux more than five decades ago. [38] Fujita and co-workers developed a low temperature (-20 to -50 °C) reduction of thio esters by treating with diisobutylaluminum hydride (DIBALH) in hexane-dichlorometane (Eq. 17) [39]. The authors also reported that treatment of thiol esters with NaBH4 in aqueous THF at room temperature gave alcohols in high yields (Eq. 18). [Pg.101]

In 1990, Fukuyama and co-workers established a palladium-mediated reduction of thiol esters to aldehydes with Et3SiH (Eq. 19) [40]. [Pg.101]

Penn and co-worker report the reduction of thiol esters with lithium. Treatment of aryl and alkyl thiol esters with lithium wire at -78 °C for 4-5 h, followed by quenching with MeOH, resulted in the exclusive formation of aldehydes (Eq. 20). The reaction mechanism seems to involve electron-transfer from lithium... [Pg.101]

See Wallace, O.B. Springer, D.M. Tetrahedron Lett., 1998, 39, 2693 for cleavage of thiol esters to thiols with NaSMe in methanol and Choi, J. Yoon, N.M. Synth. Commun., 1995, 25, 2655 for borohydride exchange resin-Pd(OAc)2 reductive cleavage of thiol esters to thiols. [Pg.610]

EtsSiH 84b (2-3 equiv.) is added at room temperature, under an argon atmosphere, to a stirred mixture of 2-5 mol% 10% Pd on carbon and a 0.5-1 M solution of thiol ester 1849 in acetone. Stirring is continued at room temperature until reduction is complete (30-60 min). The catalyst is isolated by filtration through Cehte and washed with acetone. Evaporation, and separation on a sihca gel column, gives the desired aldehyde 1850 in 91% yield [76] (Scheme 12.67). [Pg.300]

Personal communication from Dr. J. V. Karabinos. Subsequent work on the reduction of steroid acids by Spero, McIntosh and Levin (ref. 12) has shown that Raney niokel partially deactivated by acetone is particularly suitable for the desulfurization of thiol esters to aldehydes. [Pg.35]

Reductive amination of carbonyl compounds, 59, 1 71, 1 Reductive cyanation, 57, 3 Redutive desulfonylation, 72, 2 Reductive desulfurization of thiol esters,... [Pg.593]

The synthesis of the sulfur-containing intermediate 15 for the preparation of peptides XVI and XVII (77) is shown in Scheme 6. Synthetic intermediate 14 was derived from compound 6 by the reduction of the ester and ring closure after treatment with sodium hydride in dimethylforamide. The primary alcohol in compound 14 was then converted to a leaving group which was displaced by the desired thiol to give the intermediate 15. Oxidation of the resulting sulfide then afforded the corresponding sulfone for incorporation into the desired peptide XVI. [Pg.167]

A further method for reduction of carboxylic esters is the reductive cleavage of thioesters, which can be carried out under mild conditions and affords a thiol and the alcohol related to the carboxylic acid.526... [Pg.78]

Reactions of thiol esters with the three most commonly used reagents - tri-butylstannane,tris(trimethylsilyl)silane (TTMSS),and allyltributylstannane -were conducted using AIBN as an initiator. The reaction of 36 with 1.3 equiv of Bu3SnH in refluxing benzene with AIBN for 1 h led to complete consumption of the substrate and clean formation of the cyclization and reduction products (39 and 40, respectively, see Fig. 3) in a ratio of 96 4. As anticipated, dihydro-benzothiophene 41 was also formed in this reaction. It is worth noting that 40... [Pg.107]

In bicyclic adducts (eq 1), thiol enol ethers are the direct products of oxidative decarboxylation reduction of the ester and subsequent hydrolysis of the thiol enol ethers affords a-methylene ketones (eq 5). Thus eqs (eq 4) and (eq 5) demonstrate the utility of (1) as a methoxycarbonylketene (2) or methyleneketene (3) synthon in [4 + 2] cycloaddition reactions. [Pg.386]

But we can assign to GSH more specific functions also. It participates in transpeptidations and oxidation reductions as well as in hydration-dehydration reactions. Perhaps this large variety of reactions has more in common than appears at first sight. Many of the transpeptidation reactions have been shown to occur with enzymes such as the cathepsins which require SH groups for activity. Hydrolysis of thiol esters by papain has been recently demonstrated (66) and the formation of thiol esters as intermediates in transpeptidations still remains to be explored. In the glyoxalase reaction the actual substrate may be the hydrated form of the aldehyde, in which case the reaction mechanism would be one of dehydration and hydrolysis rather than of a hydrogen shift. Thus the reaction will bear some similarity to the aconitase reaction which is stimulated by SH compounds and ferrous ions (67). [Pg.174]

Scheme 68 shows the conversion of the phenoxymethylpenicillin-derived disulfide (see Scheme 10) to penem derivative (91) (78JA8214). Of particular interest in this sequence is the reductive acylation step to afford (89) and the Wittig ring closure to give (90). The rate of the latter reaction was found to be greatly infiuenced by the steric and electronic character of both the thiol ester and the carboxyl blocking group. [Pg.334]

The most commonly employed routes for the preparation of the / -sulfatoethylsulfone group, which is the essential structural feature of vinylsulfone reactive dyes, are illustrated in Scheme 8.5. One method of synthesis involves, initially, the reduction of an aromatic sulfonyl chloride, for example with sodium sulfite, to the corresponding sulfinic acid. Subsequent condensation with either 2-chloroethanol or ethylene oxide gives the / -hydroxyethylsulfone, which is converted into its sulfate ester by treatment with concentrated sulfuric acid at 20 30 °C. An alternative route involves treatment of an aromatic thiol with 2-chloroethanol or ethylene oxide to give the /Miydroxyethylsulfonyl compound which may then be converted by oxidation into the /Miydroxyethylsulfone. [Pg.147]

Thiol esters undergo smooth reduction to give aldehydes by the Fukuyama hydrosilylation procedure, which is an alternative way to transform carboxylic acids to aldehydes. Upon treatment with Et3SiH and 10% Pd/C, a thioester underwent smooth reduction to give an aldehyde.409,410 For example, to a stirred mixture of thioester and Pd/C in acetone may be added Et3SiH at room temperature under an Ar atmosphere. Stirring is continued until the hydrogenolysis is complete (0.5-1 h) (Scheme 4.117). [Pg.182]


See other pages where Reduction of thiol esters is mentioned: [Pg.1689]    [Pg.1298]    [Pg.151]    [Pg.591]    [Pg.244]    [Pg.1689]    [Pg.1298]    [Pg.151]    [Pg.591]    [Pg.244]    [Pg.159]    [Pg.246]    [Pg.1401]    [Pg.541]    [Pg.159]    [Pg.527]    [Pg.174]    [Pg.265]    [Pg.538]    [Pg.279]    [Pg.456]    [Pg.290]    [Pg.100]    [Pg.533]    [Pg.940]    [Pg.1550]   
See also in sourсe #XX -- [ Pg.122 , Pg.214 , Pg.496 ]




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