Methyl aldehyde

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... 

Table 9. Anti-Cram Alkylation of a-Methyl Aldehydes I R2M - 78 °C...

In the haloform reaction, methyl ketones (and the only methyl aldehyde, acetaldehyde) are cleaved with halogen and a base. The halogen can be bromine, chlorine, or iodine. What takes place is actually a combination of two reactions. The first is an example of 12-4, in which, under the basic conditions employed, the methyl group is trihalogenated. Then the resulting trihalo ketone is attacked by hydroxide ion ... 

Mukaiyama reactions of a-methyl aldehydes proceed through an open TS and show a preference for the 3,4-syn stereoisomer, which is consistent with a Felkin TS.80... 

Advantage of this chelation has been taken in the construction of compounds with several contiguous chiral centers. Z-2-Butenyl trifluorosilanes give sy -l,3-diols on reaction with a fz -(3-hydroxy-a-methyl aldehydes.111 The stereoselectivity is consistent with a chelated bicyclic TS. 

The corresponding syn-P-hydroxy-a-methyl aldehydes do not react through a chelated TS,112 which appears to be due to steric factors that raise the bicyclic TS by several kcal relative to the anti isomers. The monocyclic six-membered TS does not incorporate these factors and the syn isomer reacts through a monocyclic TS. Figure 9.3 depicts the competing TSs and their relative energies as determined by MNDO calculations. 

With this method, that is, the reaction of tartaric acid ester-modified crotyl-boronates with chiral 2-methyl aldehydes, the C-19 to C-29 fragment of rifa-mycin has been constructed similarly.76... 

Addition to chiral aldehydes. Brown et al.2 have examined the reaction of the chiral aldehyde 2 with the (E)- and (Z)-isomers of (+)- and (- )-l. The stereochemistry at the newly formed bond between C4 and C5 is controlled by the chirality of 1. The reaction affords two of the possible diastereomeric products in 64% de. Similar results have been reported by Roush et al. for reaction of a (3-alkoxy-a-methyl aldehyde. 

Synonyms AI3-26806 BFV Caswell No. 465 CCRIS 315 Dormol EINECS 200-001-8 EPA pesticide chemicai code 043001 FA Fannoform Formalin Formalin 40 Formalith Formic aldehyde Formol FYDE HOCH Ivalon Karsan Lysoform Methaldehyde Methanal Methyl aldehyde Methylene glycol Methylene oxide Morbicid NCI-C02799 Oxomethane Oxy-methylene Paraform RCRA waste number U122 Superlysoform UN 1198 UN 2209. 

Methyl aldehyde, see Formaldehyde (Methylamino)benzene, see Methylaniline... 

Synonyms Methanal formic aldehyde oxomethane oxymethylene methylene oxide methyl aldehyde... 

The present method is practical and efficient as it employs readily available enantioenriched propargylic alcohols as precursors to the allenylindium reagents. With achiral aldehydes the diastereoselectivity is high for branched aldehydes, moderate for unbranched aldehydes, and low for benzaldehyde (Table I). With cHral a-methyl aldehydes the additions proceed under effective reagent control to afford anti adducts of high ee and with excellent diastereoselectivity (eq. 1 and 2). Comparable results were obtained with 3 1 dimethyl sulfoxide-tetrahydrofuran (DMSO-THF) as the solvent. 

Bromo substituents in the 6- and 6 -positions of 2,2 -bipyridines are particularly reactive, being readily converted to amino,cyano, ° al-koxyl, hydrazino, chloro, and hydrogen groups and by way of the corresponding lithio derivatives to carboxyl, methyl, aldehyde or alkylcarbonyl, and other groupings. 6,6 -Dibromo-2,2 -bi-pyridine also reacts with the disodium derivatives of polyethylene glycols to give crown ethers akin to 100, and 6,6 -bis(chloromethyl)-2,2 -bi-pyridine " and the derived 6,6 -bis(mercaptomethyl)-2,2 -bipyridine... 

Firstly, copper(I) preferentially formed complexes that incorporated the methylated aldehyde. All three possible products shown in Scheme 1.2 were observed in the reaction of Scheme 1.14. The two aldehydes were incorporated into the product mixture in a molar ratio of 30 70, which indicates a slight thermodynamic preference for the incorporation of the methylated aldehyde, whose more electron-rich character would allow ligands that incorporate this residue to better stabilize the cationic copper(I) center. 

Scheme 1.14 The choice of copper methylated aldehyde was preferentially incorporated into copper(l) complexes in aqueous solution.

A third driving force for the observed selectivity, complementing and amplifying copper s choice of the methylated aldehyde, is the preference of iron(II) to incorporate the nonmethylated aldehyde into complexes of type 14. As shown in Scheme 1.16, the addition of iron(II) to a mixture of triamine and both aldehydes gave a product mixture in which nonmethylated and methylated aldehydes are present in a 3 97 ratio following equilibration. Only the two products shown in Scheme 1.16 were observed in the product mixture. The reaction of Scheme 1.16 thus deviates substantially from a statistical mixture of products indeed, only two of the expected four products are observed to form. No evidence was found of complexes incorporating two or three equivalents of methylated aldehyde. 

Synonyms and trade names formaldehyde 37%, Formalin, morbicid acid, methylene oxide, methyl aldehyde... 

Chiral a-methyl aldehydes. Reaction of optically active 2,3-epoxy alcohols with AI(CH,)i results in a mixture of two diols that arc not separable by conventional chromatography. However, the 1,2-diol is oxidized by NaI04 to a chiral a-methyl aldehyde, which is easily separated from the 1,3-diol. 

METHYLAL see MGA850 METHYL ALCOHOL see MGB150 METHYL ALDEHYDE see FMXEOO... 

Additions of the presumed /3-oxygenated allylic trichlorostannane to a-methyl, a-benzyloxy and /3-benzyloxy aldehydes are characterized by high reagent-controlled diastereoselectivity (Eq. 48) [70]. In the several examples examined aldehyde facial attack is little influenced by the resident chirality of the aldehyde. The result is particularly striking with the a-methyl aldehyde where the syn, syn adduct is the product of Felkin-Ahn addition and the anti, syn adduct is the anh-Felkin-Ahn or chelation-controlled adduct. 

Trimethylsiloxycyclopropanes, readily available from silyl enol ethers and carbene or carbenoid species, constitute, now, very useful synthetic intermediates . Thus, they undergo acid-, base-inducedor thermal ring-opening into a-methylated aldehydes and ketones in very good yields. The reaction is highly regiospecific in the case of an unsymmetrical ketone, monomethylation can be oriented either to the a- or a -position (equation 58) °°. This sequence has been applied to ethylenic ketones and in the steroid field . ... 

Gennari, C., Vieth, S., Comotti, A., Vulpetti, A., Goodman, J. M., Paterson, I. Diastereofacial selectivity in the aldol reactions of chiral a-methyl aldehydes a computer modelling approach. Tetrahedron 1992, 48,4439-4458. 

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