Halides aldehydes, synthesis

SENARY Conjugated Aldehyde Synthesis Formation ot polyunsaturated aldehydes trom vinyl halides and enamlnoaldehydes... 

SOMMELET Aldehyde synthesis Aldehyde synthesis from primary alkyl halides with hexamethylene tetramine. 

The (V-methyldihydrodithiazine 125 has also been used as an effective formyl anion equivalent for reaction with alkyl halides, aldehydes, and ketones (77JOC393). In this case there is exclusive alkylation between the two sulfur atoms, and hydrolysis to give the aldehyde products is considerably easier than for dithianes. However, attempts to achieve a second alkylation at C2 were unsuccessful, thus ruling out the use of this system as an acyl anion equivalent for synthesis of ketones. Despite this limitation, the compound has found some use in synthesis (82TL4995). 

Koch aldehyde synthesis) introduces the H-—C=0 function into reactive aromatic compounds such as 2-naphthalenol. The necessary reagents are HCN, HCl, and a metal-halide catalyst (ZnCI2 or AICI3), and the initial product must be treated with... 

Addition tube, 20, 21 Alanine, /3-(3,4-dihydroxyphenyl)-N-METHYL-, 22, 89, 91 Alcoholic hydrochloric acid, 22, 77, 83 standardization, 22, 80 Alcoholysis, 20, 67 Aldehyde synthesis, 20, 14 from acid chlorides by Rosenmund reaction, 21, 84, 87, 88, 110 Alkylation of thiourea, 22, 59 Alkylchlororesorcinols, 20, 59 Alkylene bromide, 20, 24 S-Alkylthiuronium halides, 22, 60 dl-ALLOTHREONINE, 20, 10 ... 

Another commercial aldehyde synthesis is the catalytic dehydrogenation of primary alcohols at high temperature in the presence of a copper or a copper-chromite catalyst. Although there are several other synthetic processes employed, these tend to be smaller scale reactions. For example, acyl halides can be reduced to the aldehyde (Rosemnund reaction) using a palladium-on-barium sulfate catalyst. Formylation of aryl compounds, similar to hydrofomiylation, using HCN and HQ (Gatterman reaction) or carbon monoxide and HQ (Gatterman-Koch reaction) can be used to produce aromatic aldehydes. 

Hydrolysis yields the terminal acetylene (3) carbonation yields the propargylic acid (4). Synthesis of a wide variety of acetylenes is possible by the reaction of the intermediate lithium acetylides with other electrophiles (alkyl halides, aldehydes, ketones). 

The A -diphenylmethylene protection has also been used in the solid-phase mode for the synthesis of either unnatural amino acidst 1 or peptides (Scheme 67)J 1 Thereby, both Merrifield or Wang resins were used and the best base proved to be the organic soluble, nonionic phosphazene bases of Schwesinger, e.g. 2-tert-(butylimino)-2-(ethylamino)-l,3-di-methyl-l,3,2-diazaphosphinane (BEMP). As electrophiles alkyl halides,aldehydes, and Michael acceptors have been used. 

As in the Grignard reaction we may use any aliphatic aldehyde, ketone, ester or acid chloride, or an aryl compound of the same type and also, we may use either alkyl magnesium halides or aryl magnesium halides the synthesis makes possible the preparation of practically any desired secondary or tertiary alcohol either aliphatic or aromatic. Also if formaldehyde, in the form of its polymer, tri-oxy methylene, is used in the second reaction we will obtain primary alcohols. In the third reaction formic acid esters yield secondary instead of tertiary alcohols. These syntheses of alcohols by the Grignard reaction give us an idea of its importance in synthetic work. 

The tin enolates are useful in organic synthesis as a mild source of the nucleophilic enolate group in its reaction with alkyl or acyl halides, aldehydes or enones. The tin enolates are less basic than the lithium enolates, and more reactive though rather less easy to handle than the silicon enolates.105-113... 

Aldehyde synthesis.2 The carbanion generated from this reagent (1) reacts with an alkyl halide to give an aldehyde dimethyl mercaptal S-oxide (2). This product is easily... 

Aldehyde synthesis. The reagent can be used to convert a halide or tosylate into the corresponding aldehyde ... 

Krohnke aldehyde synthesis. Transformation of benzyl halides into aldehydes via their pyri-dinium salts which, on treatment with p-nitrosodi-methylaniline, give nitrones. Hydrolysis of the nitrones yields aldehydes. 

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