Methyl compounds, reduction

The isolation of the 6-deoxytetracyclines (44) led to other chemical modifications of (1). 6P-Deoxytetracycline [5614-03-9] (13), prepared by catalytic hydrogenolysis of tetracycline (1), resulting ia an iaversion (45) of the configuration at the C-6 position, but retention of antibacterial activity. Catalytic reduction (7,8) of the 6-methylene derivative (14) yields both the 6a-methyl (15) and 6P-methyl compound (13). The 6a-isomer (15) is reported (7,45) to be more active than the 6P isomer (13). The a-isomer, doxycycline (6), is an example of a semisynthetic tetracycline that has become commercially useful. 

The styrene double bond in 9(ll)-dehydroestradiol 3-methyI ether (1) or its 8-dehydro counterpart is reduced by potassium or lithium in ammonia without affecting the aromatic ring estradiol 3-methyl ether (2) is formed from both compounds. Reduction of the corresponding 17-ketones occurs with partial or complete reduction of the carbonyl group. Lithium... 

Most dienones that have been reduced have structures such that they cannot give epimeric products. However, reduction of 17 -hydroxy-7,17a-dimethyl-androsta-4,6-dien-3-one (63) affords 17 -hydroxy-7j9,17a-dimethylandrost-4-en-3-one (64), the thermodynamically most stable product, albeit in only 16% yield. The remainder of the reduction product was not identified. Presumably the same stereoelectronic factors that control protonation of the / -carbon of the allyl carbanion formed from an enone control the stereochemistry of the protonation of the (5-carbon of the dienyl carbanion formed from a linear dienone. The formation of the 7 -methyl compound from compound (63) would be expected on this basis. 

The reduced alkyl complexes are reoxidized by O2 to the iron(lll) alkyls. The corresponding diamagnetic phthalocyanine iron(ll) alkyl complexes, rFe(Pc)R), were prepared by two-electron reduction of Fe(Pc) by LiAIFl4 to give [Fe(Pc) (actually the Fe(I) phthalocyanine radical anion) followed by reaction with Mel, Etl or i-PrBr. The methyl compound, [Fe(Pc)CHi] was characterized by X-ray crystallography. ... 

In order further to determine whether the reductive, [ C]methylation technique possibly perturbs the structure of these glycoproteins and glycopeptides, natural-abundance C-n.m.r.-spectral data were obtained for unmodified, and for reductively [ C]methylated, compound 10 (for struc-... 

The usual range of reactions has been recorded for the aldehydes of dibenzothiophene. Oxidation yields the corresponding acid, - reduction with LAH the corresponding alcohol, reduction under Huang-Minlon conditions the corresponding methyl compound, and two examples of the Cannizarro reaction have been described. ... 

Like any aldehydes aromatic aldehydes undergo Clemmensen reduction [758, 778] and Wolff-Kizhner reduction [759, 774] and give the corresponding methyl compounds, generally in good yields. The same effect is accomplished by conversion of the aldehydes to p-toluenesulfonyl hydrazones followed by reduction with lithium aluminum hydride (p. 106). 

Ames and co-workers have reported the synthesis of some aminoethyl indolizines.141 Workers at Keele University have investigated the preparation of hydroxymethyl and aminomethyl derivatives.142 They obtained the 2-, 3-, and 6-hydroxymethyl compounds by lithium aluminum hydride (LAH) reduction of the esters. However, compound 93 gave inseparable mixtures on reduction, and whereas the 2-amino-methyl compound could be made by reduction of the corresponding... 

The iV-4-(benzotriazolylmethyl)-tetrahydro-l,4-benzodiazepine 59 reacted smoothly with Grignard reagents in THF to provide convenient access to substituted homologues in good yield (Scheme 25) <2002J(P1)592>. The benzo-triazole moiety can be removed reductively with NaBFLr to provide the simple jV-methyl compound, while reaction with triethyl phosphite and ZnBr2 in dry THF gave the diethylphosphonate derivative. 

Reduction of the cyclic allene 72 by sodium metal affords the polycyclic allyl anion 37, which was crystallized and characterized. Reaction with methyl iodide resulted in the formation of the methylated compounds 38 and 39 (Scheme 2) <1996OM3480>. 

Hepten-2-one, 6-methyl-, phytochemical reduction of, IV, 82 Heptonitrile, 7-desoxy-, IV, 149 Heptose, origin of name, III, 11 Heterocyclic compounds, phytochemical reduction of, IV, 90 Heterolevulosan, III, 119, 120... 

At present we are conducting experiments with XIX, XX, and other flavins with crude hydrogenase (quite air labile) kindly provided by Wolfe. Initial results demonstrate ready reduction of biological and synthetic Fo (XX) at approximately 200 nmol/min/mg while the 7-methyl compound, XIX, is reduced tenfold more slowly (at equivalent 20fiM concentration). Studies are underway to investigate ratedetermining steps, flavin specificity, stereochemistry, and mechanism of redox transfer between H2 and F420 as well as its reoxidation by NADP. 

Catalytic hydrogenation of compound (44) and LAH reduction of compound (45) both yielded the 1,2,3,4-tetrahydro-derivative whereas Zn/acetic acid or electrochemical reduction gave the air-sensitive 1,4-dihydro-compounds <87CJC1619>. Instead of the formation of the expected 5-methyl compound, MeLi attacked the highly hindered 2-position of compound (24 R = Bul) to yield compound (25 R = Me) <84LA133>. 

A route to /3-methyl-tetrahydroberberines has been developed from the hydra-stinine derivative (72), which can be acylated with the dimethoxyhomophthalic anhydride (73) to give acid (74). Reduction of this with lithium aluminium hydride followed by further reduction of the toluene-p-sulphonyl ester of the resulting hydroxymethyl compound yields the 13-methyl compound.91 An essentially similar synthesis of oxoberberines bearing a carboxy-group at C-13, of general type (74), has been reported by other workers.92... 

Reduction of —CH2N(CH3)i to —CH3 The quaternary ammonium salts of Mannich bases are reduced to the corresponding methyl compounds by NaBHaCN in HMPT. 

Reduction of (427) with lithium in liquid ammonia followed by trapping of the enolate with methyl iodide gave the pure 10/3-methyl compound, which was transformed into ( )-D-homotestosterone (428) by successive treatment with dilute aqueous acid at room temperature and with hot dilute aqueous methanolic sodium hydroxide. To synthesize ( )-progesterone, the carbonyl group of (428) was protected as its dioxolane, the alcohol oxidized, the derived 17a-ketone reacted with methylmagnesium bromide, the tertiary alcohol dehydrated, and the ketone deprotected to furnish the D-homo-17a-methyl-... 

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