Synthesis aldehydes

Asaronealdehyde (2,4,5-trimethoxy-benzaldehyde) can be produced in the following way Methylate resorcinol. Product is 1,3-di-MeO-benzene. Do a Vilsmeyer aldehyde synthesis with POCI3/N-methylformanilide to obtain 2,4-di-MeO-benzaldehyde. Brominate and treat as described above to obtain asaronaldehyde. 

Aldehyde Synthesis. Formylation would be expected to take place when formyl chloride or formic anhydride reacts with an aromatic compound ia the presence of aluminum chloride or other Friedel-Crafts catalysts. However, the acid chloride and anhydride of formic acid are both too unstable to be of preparative iaterest. 

Aromatic and heterocycHc compounds are formylated by reaction with dialkyl- or alkylarylformamides in the presence of phosphoms oxychloride or phosgene (Vilsmeier aldehyde synthesis) (125). The Vilsmeier reaction is a Friedel-Crafts type formylation (126), since the intermediate cation formed by the interaction of phosphoms oxychloride with formamide is a typical electrophilic reagent. Ionic addition compounds of formamide with phosgene or phosphoms oxychloride are also known (127). 

The Gattermann-Koch reaction when appHed to alkenes or alkanes gives ketones or acids but not aldehydes. However, the Vilsmeier aldehyde synthesis can be appHed to aUphatic compounds. For example, 1,2-diaLkoxyethylenes react with /V-methy1foTmani1ide and POCl to give alkoxymalondialdehydes ... 

Although POCl is the traditional reagent in the Vilsmeier aldehyde synthesis, phosgene may be employed (27—29). 

Thiazoline, trans-2-amino-4,5-dimethyl-synthesis, 6, 310 2-Thiazoline, 2-aryl-synthesis, 6, 307, 308, 309 2-Thiazoline, 2-arylamino-tautomerism, 6, 248 2-Thiazoline, 2-dialkylamino-synthesis, 6, 308 2-liiiazoline, 5-imino-synthesis, 5, 461 2-"niiazoline, 2-mercapto-hydrolysis, 6, 272 oxidation, 6, 272 synthesis, 6, 307 2-Thiazoline, 2-methyl-aldehyde synthesis from, 1, 469 2-Thiazoline, 2-methyl-acetylation, 6, 270 acylation, 6, 270 H NMR, 6, 243... 

Thieno[3,2-c]pyridine, 4,5,6,7-tetrahydro-biological activity, 4, 1015 Thieno[2,3-6]pyridine-2-carb aldehyde synthesis, 4, 1014... 

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

BODROUX - CHICHIBABtN Aldehyde synthesis Aldehyde synthesis Irom Grignard reagents and trialkyl oitholormate... 

BOUVEAULT Aldehyde synthesis Aldehyde synthesis Irom Gngnard or Li derivatives with a lormarmde... 

BORSCHE - BEECH Aromatic Aldehyde Synthesis Synthesis of aromatic aldehydes and of akyl aryl ketones from aldoximes or semcaibazones and aromatic dlazonum salts... 

EHRLICH - SACHS Aldehyde Synthesis Formation of o-nitrobenzaldehydes from o-nitrotoluenea. 

Alpha amino acids (and aldehydes) synthesis by reaction of an alpha keto add with another amino acid (Herbst-EngeO or by reaction of a keto acid with ammonia tmdef reducing conditions (Knoop-Oe sterling). 

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

SONN MULLER Aldehyde synthesis Aldehyde synthesis from amides or ketoximes, by reduction of irmno chiondes. 

STEPHEN Aldehyde synthesis Aldehyde synthesis from nitnies and SnClj - HCI... 

We ve already discussed two methods of aldehyde synthesis oxidation of primary alcohols and oxidative cleavage of alkenes. 

A third method of aldehyde synthesis is one that we ll mention here just briefly and then return to in Section 21.6. Certain carboxylic acid derivatives can be partially reduced to yield aldehydes. The partial reduction of an ester by dhsobutylaluminum hydride (DIBAH), for instance, is an important laboratory-scale method of aldehyde synthesis, and mechanistically related processes also occur in biological pathways. The reaction is normally carried out at —78 °C (dry-ice temperature) in toluene solution. 

Prostaglandins 624, 725, 960 Prostanoids 620 Protonation 565-567, 1049 photochemical 882 Pseudopotential methods 15, 16 Pummerer rearrangement 240, 243, 470, 843 Pyramidal inversion 602, 604 Pyrazolenines 749 Pyridazine oxides 640 Pyridine aldehydes, synthesis of 310 Pyridine oxides 640 Pyrolysis 102-105 of sulphones 110, 679-682, 962 of sulphoxides 739, 740 Pyrroles 265, 744... 

The ion 133 also reacts with epoxides to form y-hydroxy aldehydes after reduction and hydrolysis,and with aldehydes and ketones (16-41). Similar aldehyde synthesis has also been carried out with thiazoles " and thiazolines (five-... 

Compounds 137 and 138 are thus synthons for carboxylic acids this is another indirect method for the a alkylation of a carboxylic acid, representing an alternative to the malonic ester synthesis (10-104) and to 10-106 and 10-109. The method can be adapted to the preparation of optically active carboxylic acids by the use of a chiral reagent. Note that, unlike 132, 137 can be alkylated even if R is alkyl. However, the C=N bond of 137 and 138 cannot be effectively reduced, so that aldehyde synthesis is not feasible here. ... 

Ring contractions, such as the Tavorskii reaction on (38), or the cyclopentane aldehyde synthesis on p 374... 

Drivers Ibr Performing Derivatized Aldehyde Synthesis in Micro Reactors... 

Beneficial Micro Reactor Properties for Derivatized Aldehyde Synthesis... 

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