Alcohols thiol-substituted

Additional NMR information may be useful in difficult enantiomer analyses of alcohols, thiols, and primary and secondary amines. Reaction 32 illustrates the process for a chiral primary amine, RNIF, undergoing N-substitution with chiral reagent 185. Besides the 31P NMR spectra of the diasteroisomers 186, also 1H, 13C and 19F spectra may be taken. Addition of sulfur or selenium to the NMR tube will afford diasteroisomers 187, for which the corresponding spectra can also be taken397. 

In the presence of a catalytic amount of methanethiolate-bridged diruthenium complex (la abbreviated as met-DIRUX), reactions of propargylic alcohols (2) with a variety of heteroatom-centered nucleophiles such as alcohols, thiols, amines, amides, and diphenylphosphine oxide gave the corresponding propargylic substituted... 

Trityl resins are particularly suitable for immobilization of nucleophilic substrates such as acids, alcohols, thiols, and amines. They are quite acid-sensitive and are cleavable even with acetic acid this is useful when acid-labile protecting groups are used. The stability of trityl resin can be tailored by use of substituted arene rings, as shown by chlorotrityl resin, which furnishes a more stable linker than the trityl resin itself. Steric hindrance also prohibits formation of diketopiperazines during the synthesis of peptides. Orthogonality toward allyl-based protective groups was demonstrated in the reverse solid-phase peptide synthesis of oligopeptides [30] (Scheme 6.1.4). 

Several heteroatom nucleophiles, for example, amines, alcohols, thiols, carboxylates, and dialkylphosphines, undergo Michael addition reactions with alkene- and alkyne-substituted carbene complexes. Reaction of alkyne-substituted chromium carbenes with urea affords products derived from Michael... 

In the simplest of these, jS-enaminones are synthesized (equation 129) by the addition of amines to 1,3-diketones or /3-ketoesters. The reaction has been apphed to the Friedlander synthesis of quinolines by condensation of the enaminone and other carbonyl present in the substrate. Substituted pyrroles in equation (130) can be obtained as well when a propargyl group is present, by addition of the enaminone to the triple bond. Alcohols, thiols, and secondary phosphines have been also tested as nucleophiles with good results. A particularly interesting case is found in the condensation of indoles with 1,3-diketones to give substituted indol derivatives in equation (131). ... 

Reacthity of chlorotropylium cations with nucleophiles. Alkuxy-, alkylthio-, and N-alkyl-N-arylaminotropylium. salts are prepared by reaction of chlorotropybum salts with alcohols, thiols, and N-alkyl-N-arylamines, respectively. With dimethylamine or with benzenesulfonamides chlorotropylium salts rearrange to yield bis(dimethyl-amino)phenylmethane or N-benzylidencsulfonamides. It is postulated that the formation of chlorocycloheptatrienes (IA, IB, 1C) is kinetically controlled, whereas substituted tropylium ions (3) are formed under thermodynamic control. 

Mineral acids such as hydrochloric acid undergo addition to cycloproparenes to give benzylic derivatives in almost quantitative yield. Weaker acids such as alcohols, thiols and amines undergo a similar addition in the presence of a catalytic amount of silverfl). The addition products of the simple cycloproparenes are usually of no preparative interest but the silver(I)-catalyzed electrophilic addition of methanol or acetic acid to 1 //-3,8-methanocyclopropa[l 0]an-nulene opens a simple access to 3-substituted l,6-methano[10]annulenes la,b and their 11,11-difluoro derivative Ic. ... 

Thiols are generally regarded as better nucleophiles than alcohols in substitution reactions. Accordingly, Hongmei Li investigated the use of thiols as nucleophiles in... 

Substitution reactions. Replacement of the hydroxyl group of l-alkyn-3-ols on reaction with alcohols, thiols, and amines is accomplished at room temperature in the presence of binuclear complex 1 and NH4BF4. 

Like their amine analogues (Section 20.4.2.1) thiol-substituted alcohols may act as bidentates with chelation often leading to polymeric products. The stability constants of the Cd" complexes of both 2-mercaptoethanol (mel) and 3-mercapto-1,2-propanediol (mpd) have been determined, with polymeric structures being concluded similar to those of the previously determined Ni and Zn compounds. Similar data for the Pb" complexes showed polymer formation with mpd and gave evidence for Pb-mel species with at least five different metal ligand ratios. Reaction of the pertechnetate(VII) ion [Tc04] with sodium dithionite and 2-mercaptoethanol results in the... 

Miscellaneous.- A simple method to resolve racemic l,l -binaphthalene-2,2 -diol involves reaction with menthyl phosphorodichloridite (139) and separation of the diastereomeric phosphites by crystallisation from ether. The new cyclic chlorodiaminophosphine (140), prepared in and two new cyclic triaminophosphines (141) have been used to determine the enantiomeric purity of chiral alcohols, thiols, and amines by means of Ip n.m.r. New optically pure phosphites used for Rh catalysed asymmetric hydroformylation reactions are (142), two diastereomers of (143), and (144) the diphosphinite (145) was similarly employed. Some new cyclic aminophosphines (146) were prepared for use as ligands in asymmetric Pd catalysed allylic substitution reactions. 

Michael-type addition of thiols to the dehydroproline double bond of pristinamycin IIa was investigated. Attempted reaction with alkyl thiols, substituted phenyl thiols, ethyl mercaptoacetate or hydroxy-substituted alkyl thiols using standard conditions [128] (but at room temperature) was unsuccessful. Moderate yields (up to 50%) to conjugate addition products from reaction of pristinamycin 11 with these thiols (Scheme 22) were obtained when the reaction was carried out in the presence of N,N-dimethylethanolamine (see below for discussion of the stereochemistry associated with the conjugate addition products). With sterically hindered thiols, for example, 2-mercapto-pyran, no reaction was observed even under catalytic conditions. Similar results to those described above were obtained for reaction of either of the alcohols (60) or (61). 

The second benzotriazolyl group in the intermediates obtained could be further substituted with a different primary or secondary amine, alcohol, thiol, or Grignard reagent to produce a variety of... 

The thiolate bridged diruthenium complex [(r] -C5Me5)RuCl(jLz-SR)2Ru(/] -C5Me5)Cl] 211, or its derivative with various anions, proved to be a very efficient catalyst for substitution of propargylic alcohols with a number of nucleophiles. The substitution of propargylic alcohols proceeds with heteroatom nucleophiles such as alcohols, thiols, amines, amides, and phosphineoxides to give the corresponding ethers 212, thioethers 213, amines 214, amides 215, and phosphineoxides 216 (Scheme 97) [135]. Carbon nucleophiles such ketones and... 

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