Dimethoxymethyl

Uracil, 6-dimethoxymethyl-3-methyl-2-thio-synthesis, 3, 113 Uracil, 1,3-dimethyl-dimers, 3, 74 Uracil, 3,6-dimethyl-synthesis, 3, 106, 110 Uracil, 5-fluoro-... 

C. 2-(Dimethoxymethyl)-3-phenyl-2H-azirine. The crude product (71-75 g., 0.32-0.34 mole) obtained from Part B is heated at reflux in 11. of chloroform in a 2-1., round-bottomed flask for 12 hours (Note 9). The solvent is removed with a rotary evaporator and the crude residue... 

Pentanenitrile oxide, BuCNO, formed in situ from 1-nitropentane, PhNCO and Et3N in benzene, added stereo- and regioselectively to 8-.vv7/-(dimethoxymethyl)-3-oxo-2-oxabicyclo[3.2. l]oct-6-ene to give 75% of the tricyclic lactone 111 (276). Introduction of a methoxycarbonyl group into the plane asymmetrical double bond of 2,3-dioxa- and 2,3-oxazabicyclo[2.2.2]oct-5-enes, brought about a clear-cut increase in syn selectivity of their reactions with 1,3-dipoles (277). 

When the pyrrolo[l,2-c]oxazole 269 was treated with trimethyl orthoformate in the presence of BF3 Et20, in dichloromethane at — 78 °C, a mixture of compounds was obtained from which the expected 5-dimethoxymethyl derivative, 270, was isolated in poor yield (12%) with another dimethoxylated compound 271 (23%). The formation of 271 could be explained by the addition of the formyl cation equivalent at C-7, followed by the protonation at C-6 of the resulting enamide 272 leading to the electrophilic iV-acyliminium ion 273 (Scheme 40). The regioselectivity of this electrophilic addition of trimethylorthoformate to the silyloxypyrrole 269 at C-7, in a non-vinylogous manner, is unusual <1999TL2525>. 

Although it was not possible to verify whether this product is formed under kinetic or thermodynamic control, the authors suggest119 that if 90 arises from a kinetically controlled reaction, its formation could be rationalized on the basis of the stability of the involved intermediate. The bridged intermediate i is expected to be more stable than ii (equation 100) owing to the effect of the dimethoxymethyl substituent. 

The hallucinogens generally fall into two chemical classes. The indole alkylamines include LSD, psilocybin, psilocin, dimethyltryptamine (DMT), and diethyltrypta-mine (DET), all of which are structurally similar to serotonin. The other chemical subclass of hallucinogens contains phenylethylamine derivatives such as mescaline, MDMA, MDA, and DOM (dimethoxymethyl amphetamine). A related stimulatory hallucinogen, PCP, is a piperidine analogue that produces unique effects. 

Kolb and Barth 229) synthesized oc-substituted optically active amines or amino acids (223). Again the authors employed a derivative of naturally occurring (S)-proline, namely (—)-(S)-l-dimethoxymethyl-2-methoxymethyl-pyrrolidine (221) as chiral auxiliary agent. The metalation of the amidines (160) leads to azaallyl anions homologous with (222). After alkylation and hydrolysis, the desired a-substituted amines and amino acids, respectively, are obtained with some stereoselectivity. 

Formyl-2-methylfuran was converted in 75% yield into derivative 319 by electrolytic methoxylation. A corresponding mixture of cis-diols (320) was treated with Dowex W-50 ion-exchange resin in methanol for four days, to afford 5-deoxy-3-C-(dimethoxymethyl)-DL-eryf/rro-4-pentulose dimethyl acetal (321). Reduction of this compound with lithium aluminum hydride or sodium borohydride gave a mixture of 5-deoxy-3-C-(dimethoxymethyl)pentoses, which was separated by column chromatography on silica gel, to give206 DL-streptose tetramethyl acetal (322) and the isomeric 5-deoxy-3-C-(dimethoxy-methyl)-DL-ribose dimethyl acetal 323 (hjxo ribo = 13 7). Detailed, combined gas-liquid chromatographic-mass spectrometric analysis of the compounds related to streptose (in the form of their trimethyl-silyl derivatives) has been described.207... 

The sequence rules described thus far can be used without ambiguity in most of the examples we are likely to meet. The important thing to remember is to look at the kind of atoms attached as far out as necessary. Suppose we have to compare the aldehyde group, —CH=0, with the dimethoxymethyl group, CH(OCH3)2. The first atoms are the same (C), the second atoms are the same [O, (O), H], and the difference arrives at the third-atom level where we are comparing lone pairs (priority zero) with carbons. Thus—CH(OCH3)2 outranks —CH=0. 

Regiospecific dimethoxymethylation of preformed lithium enolates is also possible by a related reaction.3 Examples ... 

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