Intermediates formyl from

Protonation of lH-pyrrolizin-l-ones appears to take place on oxygen (see Sections III,A,2 and III,A,4). The other derivative of type 258 is the Vilsmeier formylation intermediate from l-chloro-3H-pyrrolizine, the perchlorate... 

To make MDMA from the formyl intermediate obtained by the Leuckart reaction the chemist is going to have to distill it to get the clean-yellow oil first. That black crap one gets from the formamide... 

It is obvious from the examples of ipso substitution discussed above that the elimination of N02 from the ipso intermediate is greatly favoured [k2 k ), leading irreversibly to the substitution products. This is because -N02 is a stable radical. On the other hand, if in the ipso intermediate (229) both R and X form strong bonds to the carbon atom, then the intermediate may be forced to decay by other processes, i.e. neither revert to (228) nor undergo substitution to (230). An example is provided by the reaction of the dialdehyde (239) with the adamantyl radical (Scheme 65) (80ACR51, 80JCS(P2)1336). The two major products are 2-adamantylthiophene-5-carbaldehyde (241 19%) and 2-adamantyI-thiophene-3,5-dicarbaldehyde (244 56%). The formation of both can be explained from the common ipso intermediate (240). The loss of the formyl group from this to form (241)... 

Pichler and Schulz were the first to suggest that the initial step in metal-catalyzed CO/H2 reactions might be the migration of catalyst-bound hydride to CO to yield a formyl intermediate [Eq. (1)] (3). The alkyl ligand in many isolable metal carbonyl alkyls can similarly be induced to migrate to coordinated CO (4. ). Thus, Eq. (1) has some precedent in homogeneous chemistry. Other suggestions for the involvement of formyl intermediates have come from Wender (6) and Henrici-Olive and Olive (7). 

In ergosterol biosynthesis, side chain alkylation of lanosterol normally takes place to build 24-methylenedihydrolanosterol, which itself is then the substrate for demethylation reactions at and C. The C -demethylation has been studied in detail. It is an oxidative demethylation catalyzed by a cytochrome P -system. The first step involved in this reaction is the hydroxylation of the Cj -methy1-group to form the C -hydroxymethyl derivative. A second hydroxylation and loss of water lead to the C -formyl intermediate, which is hydroxylized a third time to form the corresponding carboxylic acid. Decarboxylation does not directly take place, but proceeds instead by abstraction of a proton from C, followed by elimination and formation of a A 4-double bond. The NADPH-dependent reduction of the A14 -double bond finishes the demethylation reaction. Subsequently, demethylation at has to take place twice, followed by a dehydrogenation reaction in A" -position and isomerization from A8 to A7 and A24(28) to A22. respectively. 

The second method corresponds to moving the formyl group from the aldehyde intermediate to the methylene base, and is a standard method for preparing a merocyanine (the open form of a spiropyran). This method is useful for the reaction of the easily obtained and stable Fischer s aldehydes (2-formylmethyleneindolines) (1) with ketomethylene compounds such as 2-hydroxybenzofuran (2) or 2-hydroxybenzothiophene where the corresponding hydroxyaldehyde is difficult to obtain (Scheme 4). These two methods include the several routes to various symmetrical and unsymmetrical spiro(dipyrans).6... 

Homophthalic acid surprisingly yields an isoquinoline upon Vilsmeier formylation, apparently by rearrangement and cyclization of the side-chain formylated intermediate (Scheme 25). This intermediate may be isolated at low temperatures.64 In a related manner the isoquinolone (87) has been synthesized from the toluic acid (86).64a... 

The short lifetime of the intermediate carbocation is indicated by the formation of formyl derivatives from vinylcyclopropane (5) with no evidence of the opening of the cyclopropane ring that would normally be expected on formation of a carbocationic site a to the cyclopropane ring. The same paper illustrates an example of double bond migration prior to formylation the major product from Vilsmeier reaction of the vinylcyclopropane 6 is the same as that from isomer 5 (Eq. 4) conversely, increasing the size of the substituent to the cyclopropane ring can cause formylation of the thermodynamically unfavored isomer, as shown for compound 7 (Eq. 5). ... 

Ethyl 4,5-Dlbenzamldopent-4-enoate (2)5 Ethyl 3-lmidazol-4(5)-ylpfopanoate 1 (9.2 g, 54 mmol) in EtOAc (140 mL) was treated with benzoyl chloride (15.7 g, 112 mmol) in EtOAc (40 mL) and 1M NaHCOs (380 mL) added simultaneously in 1 h under ice-cooling. The reaction mixture was stirred for 1 h, then a further portion of benzoyl chloride (15.7 g, 112 mmol) in EtOAc) and 1M NaHCOs (280 mL) was added in the same manner, followed by an additional portion of 1M NaHCOa (200 mL). The reaction mixture was stirred for 24 h, then the organic layer was separated, concentrated, and the residue dissolved in THF (300 mL). The THF solution was stirred with 10% NaHCOa (600 mL) for 24 h to decompose any N-formyl intermediate and to remove benzoic acid. Extraction with EtOAc. drying (Na2S04), solvent evaporation and recrystallization of the residue from EtOAc.hexane afforded 16.24 g of 2 (84%). mp 128-129X. 

Metalloformyl complexes are the most probable first organometallic intermediates in metal complex promoted reactions of H2 and CO that produce organic oxygenates. Production of large equilibrium concentrations of T Carbon bonded formyl complexes from reactions of metal hydrides with CO (Equation 6) requires that the M-H bond... 

Because of the great potential of methanol as a fuel for low-temperature fuel cells, the electro-oxidation of methanol on Pt or Pt-based alloy electrodes has been studied extensively in the past decades [112-115]. It is generally accepted that methanol is oxidized to CO2 by the so-called dual-path mechanism [112] via adsorbed CO (poison) and non-CO reactive intermediates. The formation of CO by dehydrogenation of methanol has been well confirmed, but no consensus has been reached so far on the nature of the reactive intermediates in the non-CO pathway. Various adsorbates such as CHxOH [116], -COH [116], formyl (-HCO), [117] carboxy (-COOH) [117], a dimer of formic acid [35], and COO [38] have been claimed to be the reactive intermediates from IRAS and other physicochemical measurements. However, the spectra of the reaction intermediates are not well reproduced by other groups. 

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