Thiols from aldehydes

According to Farlow, Lazier, and Signaigo195 a cobalt poly sulfide catalyst is useful for synthesis of thiols from aldehydes by means of hydrogen sulfide under hydrogenating conditions the catalyst is obtained by treating a cobalt-aluminum alloy with sodium sulfide. 

Examples of name reactions can be found by first considering the nature of the starting material and product. The Wittig reaction, for instance, is in Section 199 (Alkenes from Aldehydes) and Section 207 (Alkenes frorm Ketones). The aldol condensation can be found in the chapters on difunctional compounds in Section 324 (Alcohol, Thiol-Aldehyde) and in Section 330 (Alcohol, Thiol-Ketone). 

The addition of Grignard reagents to aldehydes, ketones, and esters is the basis for the synthesis of a wide variety of alcohols, and several examples are given in Scheme 7.3. Primary alcohols can be made from formaldehyde (Entry 1) or, with addition of two carbons, from ethylene oxide (Entry 2). Secondary alcohols are obtained from aldehydes (Entries 3 to 6) or formate esters (Entry 7). Tertiary alcohols can be made from esters (Entries 8 and 9) or ketones (Entry 10). Lactones give diols (Entry 11). Aldehydes can be prepared from trialkyl orthoformate esters (Entries 12 and 13). Ketones can be made from nitriles (Entries 14 and 15), pyridine-2-thiol esters (Entry 16), N-methoxy-A-methyl carboxamides (Entries 17 and 18), or anhydrides (Entry 19). Carboxylic acids are available by reaction with C02 (Entries 20 to 22). Amines can be prepared from imines (Entry 23). Two-step procedures that involve formation and dehydration of alcohols provide routes to certain alkenes (Entries 24 and 25). 

From the oxidative synthesis of thioesters from aldehyde and thiol ... 

A new method for the preparation of pyrrolo[2,l-c][l,4]benzothiazepine 292 starting from aldehyde 291 with an intramolecular Mitsunobu cyclization in the last step has been reported (Scheme 63 (1999T1479)). A disadvantage of this procedure is the redox nature of the Mitsunobu reaction, which is responsible for a side oxidation of the thiol group and poor isolated yields of the product. 

The formation of thioacetals from aldehydes and ketones involves the reaction with a thiol such as ethane-1,2-dithiol in the presence of a Lewis acid catalyst such as boron trifluoride eiherate. These derivatives have been described earlier. 

Ring-opening hydrolysis of thiazolidines under acidic or basic conditions gives aldehyde and amino thiol. Peptidyl aldehydes 111 were synthesized in excellent yields from thiazolidine peptides 112 using copper salts (CuO, CUCI2) in acetonitrile/water under the reducing conditions (Scheme 39) <1997TL2459>. 

The reaction of aldehydes or ketones with thiols, usually with a Lewis acid catalyst, leads to dithioacetals or dithioketals. The most common catalyst used is probably boron trifluoride etherate (BF3 OEt2). Similarly reactions that use 1,2-ethanedithiol or 1,3-propanedithiolleadto 1,3-dithiolanes, such as 18 or l,3-dithianes. " Dithioa-cetals can also be prepared from aldehydes or ketones by treatment with thiols in the presence of TiCU, SiCU, LiBp4, AKOTfls, with a disulfide RSSR (R = alkyl or aryl), or with methylthiotrimethylsilane (MeSSiMe3). " ... 

The only classes of organic materials with which COBrF has been treated are alcohols, thiols, and aldehydes. From alcohols, fluoroformates are formed consistent with Equation (16.13), and no bromoformates were detected [1555]. 

Reaction of thiols with aldehydes or ketones leads to formation of water and geminal bis(alkylthio) compounds, which, when derived from aldehydes, are known as mercaptals or, when derived from ketones, as mercaptols ... 

A new method of synthesizing thiol, selenol, tellurol esters from aldehydes via a Tishchenko-type reaction using diisobutylaluminum chalcogenoate (/-BU2AIYR, Y=S, Se, Te) has been reported it is shown in Eq. 12 [17]. 

Nnmerons flavor componnds are formed by caramelization, Maillard or Strecker reactions, or the oxidation of phenolic compounds and terpenes. Some classes of flavor componnds fonnd in frying foods are furan derivatives, pyrrole derivatives, pyrazines, thiols, snlfldes, aldehydes, and aromatic compounds from phenol oxidation (Pokomy, 1999). 

These polymers form from reactions of di thiols with aldehydes or ketones ... 

Burczyk, B. and Kortylewticz, Z. 1982. Organic sulfur compounds III. Sulfur dioxide as catalyst in the synthesis of thioacetals from aldehydes or ketones and alkanethiols, alkanedi-thiols, or hydroxyalkanethiols. Synthesis. 10 831-833. 

Aromatic halides, conversion to aromatic thiols 182-185 by reaction with thiourea 189-191 Aromatic thiols—see also Thiophenols mass spectra 330 preparation of 167-169 from aldehydes and ketones 251-256... 

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