Hydride acetyl

Eliminations from Os(CO)4RR occur by dinuclear mechanisms only if either R or R is H. A hydride on one metal is necessary to interact with a vacant coordination site on the other in the dinuclear transition state. With Os(CO)4H2, the vacant site is created by dissociation of CO. With Os(CO)4-(H)CH the vacant site is created by a facile rate-determining isomerization which we suggest is to an acetyl hydride. The unique instability of hydridoalkyl carbonyls thus is explained. The synthesis and properties of Os(CO)4(H)C2H and various polynuclear ethyl osmium derivatives show that (3-hydrogens have no significant effect on these elimination mechanisms. Dinuclear hydridoalkyls are excellent starting points for the synthesis of more complex polynuclear alkyls. 

Acetaldehyde—Acetic aldehyde—Acetyl hydrid——44 —is formed in all reactions in which alcohol is deprived of H without introduction of O. It is prepared by distilling from a capacious retort, connected with a well-cooled condenser, a mixture of HjSOj, 6 pts. HgO, 4 pts. alcohol, 4 pts. and pow dered manganese dioxid, G pts. The product is redistilled from calcium ehlorid below 50° (123° P.). The second distillate is mixed with two volumes of ether, cooled by a freezing mixture, and saturated with dry NHg there separate crystals of ammonium acetylid, CgHiO, NHi, -which are -washed with ether, dried, and decomposed in a distilling apparatus, over the water-bath, with tho proper quantity of dilute HjS04 the distillate is finally dried over calcium ehlorid and rectified below 35° (95° P.). 

The properties of chlorine azide resemble those of bromine azide. Pon-sold has taken advantage of the stronger carbon-chlorine bond, i.e., the resistance to elimination, in the chloro azide adducts and thus synthesized several steroidal aziridines. 5a-Chloro-6 -azidocholestan-3 -ol (101) can be converted into 5, 6 -iminocholestan-3l -ol (102) in almost quantitative yield with lithium aluminum hydride. It is noteworthy that this aziridine cannot be synthesized by the more general mesyloxyazide route. Addition of chlorine azide to testosterone followed by acetylation gives both a cis- and a trans-2iddMct from which 4/S-chloro-17/S-hydroxy-5a-azidoandrostan-3-one acetate (104) is obtained by fractional crystallization. In this case, sodium borohydride is used for the stereoselective reduction of the 3-ketone... 

To overcome this, the A -acetyl group is reduced with lithium aluminum hydride. The resulting basic enamine then reacts extremely rapidly and selectively with peracid. The derived epoxide is hydrolyzed very easily with alkali during the workup. 

The preparation of enamines by reduction of aromatic heterocyclic bases and their quaternary salts or of lactams is not the most useful approach (97). The lithium aluminum hydride reduction of N-acyl enamines has been used with both fruitful and unsuccessful results. A series of 3-N-acetyl -d -cholestenes (104) has been prepared by desulfurization of the appropriate thiazolidine (105) (98,99). Lithium aluminum hydride reduction of the... 

N-acyl enaminc (104, R = CHjCHj) gave an unstable enamine (106) which decomposed readily to 3-cholestanone. The steroidal N-acetyl enamines (107 and 108, R = C HjCHj) can be reduced by lithium aluminum hydride in tctrahydrofuran to the corresponding enamines (109, R = CJH5CH2) in 90 and 68% yield, respectively 100). Attempts to reduce the enamide (107, R = CH3) led to the formation of the impure enamine (109, R = CHj), which decomposed to the hydroxy ketone (110). 

Methyl-4-hydroxyquinazoline reacts with organic halides, in the presence of sodium methoxide, to give 3-substituted 2-methyl-4(3i/)-quinazolinones. The 0-acetyl derivative of 4-hydroxyquinazoline has been prepared under anhydrous conditions and gives the hydroxy compound with water or with lithium aluminum hydride. The N-3 acetyl derivative, however, is more stable and gives 3-methyl-4(31/)-quinazolinone with lithium aluminum hydride. ... 

Modification of the ketonic side chain is also consistent with retention of analgesic activity. Thus, reduction of methadone with lithium aluminum hydride affords the alcohol, 128 (apparently as a single diastereomer). Acetylation gives acetyl-methadol (129). ... 

B) A mixture of 2.4 parts of 1 acetyl-4-(4-hydroxyphenyl)piperazine, 0.4 part of sodium hydride dispersion 78% 75 parts of dimethylsulfoxide and 22.5 parts of benzene is stirred for one hour at 40°C. Then there are added 4.2 parts of cis-2-(2,4-dichlorophenyl)-2-(1 H-imidazol-1 -ylmethyl)-1,3-dioxolan-4-ylmethyl methane sulfonate and stirring is continued overnight at 100°C. The reaction mixture Is cooled and diluted with water. The product is extracted with 1,1 -oxybisethane. The extract is dried, filtered and evaporated. The residue Is crystallized from 4-methyl-2-pentanone. The product is filtered off and dried, yielding 3.2 parts (59%) of cis-1-acetyl-4-[2-(2,4-dichlorophenyl)-2-(1 H-imidazol-1-ylmethyl)-13-di-oxolan-4-ylmethoxy] phenyl] piperazine MP 146°C. 

The relationship between 20 and reserpine (1) is close like reserpine, intermediate 20 possesses the linear chain of all five rings and all six stereocenters. With the exception of the 3,4,5-tri-methoxybenzoate grouping, 20 differs from reserpine (1) in one very important respect the orientation of the ring C methine hydrogen at C-3 in 20 with respect to the molecular plane is opposite to that found in reserpine. Intermediate 20 is a reserpate stereoisomer, epimeric at position 3, and its identity was secured by comparison of its infrared spectrum with that of a sample of (-)-methyl-O-acetyl-isoreserpate, a derivative of reserpine itself.9 Intermediate 20 is produced by the addition of hydride to the more accessible convex face of 19, and it rests comfortably in a conformation that allows all of the large groups attached to the D/E ring skeleton to be equatorially disposed. 

Deethoxycarbonylation of the acetyl derivative 31 is accomplished with methanolic sodium methoxide, and the resulting (i/4-3-acetyl-l//-azepine)tricarbonyliron(0) can be methylated at nitrogen with iodomethane and sodium hydride.226... 

The reaction of l-acetyl-3-indolinone 124 with carbon disulfide in the presence of sodium hydride gave thiazolo[3,4-with hydrazine or phenylhydrazine gave 2H[ 1,2,4]triazino[4,5-a]in-dole 126 (75YZ980) (Scheme 29). 

The crystalline material was shown to be modified sesquiterpinoid (5) containing two aldehyde functions, one of which is a,/3-unsat-urated (la). It analyzed for C13H22O2 and formed the dioxime. It readily took up oxygen on standing and was converted to the diol on treatment with lithium aluminum hydride. The bisdinitrobenzoate of this diol with osmium tetroxide yielded the tetraol, bisdinitrobenzoate, which was not readily acetylated. 

These compounds are made by allowing the salt made from piperidine and sodium hydride to react with CS2 and then with an acetylated glycosyl bromide.56... 

Sequential esterification, lithium aluminum hydride reduction, and acetylation converted 84 into compound 86. cw-Hydroxylation of 86 with... 

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