Alkoxides reduction

If hydrogen gas is added to the reaction mixture of J, and 11 the hydrogenolysis reaction of thorium-to-carbon sigma bonds (J-1 22) allows interception of species 13 and thus, catalytic hydrogenation of the inserted carbon monoxide functionality. At 35 C under 0.75 atm initial H2 pressure with [JJ =9.0 x 10" M and [ 1JJ = 6.5 x 10" M, hydrogenation and isomerization are competitive and both the enolate and the alkoxide reduction product 14 are produced (eq.(13)). Under these conditions, turnover fre-... 

Survey of Aluminum Alkoxide Reductions Reported in the Literature. 205... 

SURVEY OF ALUMINUM ALKOXIDE REDUCTIONS. REPORTED IN THE LITERATURE... 

Algar-Flynn-Oyamada Reaction Allan-Robinson Reaction Allvlic Rearrangements Aluminum Alkoxide Reduction... 

Aluminum Alkoxide Reduction (see Meerwein-Ponndorf-Verley Reduction)... 

Manufacture. Hydroxypivalyl hydroxypivalate may be produced by the esterification of hydroxypivaUc acid with neopentyl glycol or by the intermolecular oxidation—reduction (Tishchenko reaction) of hydroxypivaldehyde using an aluminum alkoxide catalyst (100,101). 

Uses. The largest use of lithium metal is in the production of organometaUic alkyl and aryl lithium compounds by reactions of lithium dispersions with the corresponding organohaHdes. Lithium metal is also used in organic syntheses for preparations of alkoxides and organosilanes, as weU as for reductions. Other uses for the metal include fabricated lithium battery components and manufacture of lithium alloys. It is also used for production of lithium hydride and lithium nitride. 

Generally, the carboxyl group is not readily reduced. Lithium aluminum hydride is one of the few reagents that can reduce these organic acids to alcohols. The scheme involves the formation of an alkoxide, which is hydroly2ed to the alcohol. Commercially, the alternative to direct reduction involves esterification of the acid followed by the reduction of the ester. 

The effects of both pH and temperature of aluminum alkoxide hydrolysis on gelation is shown in Eigure 8. Addition of acid into the mixture hydrolyzed at 90°C, and by consequence reduction of pH, reduces the gelation time of the samples, whereas in mixtures hydrolyzed at room temperature, acidic addition increases gelation time. 

Titanium(III) alkoxides can be produced by photoreduction of the tetraalkyl titanates in the presence of a base, such as pyridine (180), and by reduction of tetraalkyl titanates by organosiUcon compounds containing Si—H groups (181). 

Many other examples are known of non-selective reactions of halo groups in pyridopyridazines with amines, alkoxides, sulfur nucleophiles such as hydrosulfide and thiolate ions, or thiourea, hydrazine(s), cyanide ion and dimethyl sulfoxide, or on catalytic reduction. 

Purines, N-alkyl-N-phenyl-synthesis, 5, 576 Purines, alkylthio-hydrolysis, 5, 560 Mannich reaction, 5, 536 Michael addition reactions, 5, 536 Purines, S-alkylthio-hydrolysis, 5, 560 Purines, amino-alkylation, 5, 530, 551 IR spectra, 5, 518 reactions, 5, 551-553 with diazonium ions, 5, 538 reduction, 5, 541 UV spectra, 5, 517 Purines, N-amino-synthesis, 5, 595 Purines, aminohydroxy-hydrogenation, 5, 555 reactions, 5, 555 Purines, aminooxo-reactions, 5, 557 thiation, 5, 557 Purines, bromo-synthesis, 5, 557 Purines, chloro-synthesis, 5, 573 Purines, cyano-reactions, 5, 550 Purines, dialkoxy-rearrangement, 5, 558 Purines, diazoreactions, 5, 96 Purines, dioxo-alkylation, 5, 532 Purines, N-glycosyl-, 5, 536 Purines, halo-N-alkylation, 5, 529 hydrogenolysis, 5, 562 reactions, 5, 561-562, 564 with alkoxides, 5, 563 synthesis, 5, 556 Purines, hydrazino-reactions, 5, 553 Purines, hydroxyamino-reactions, 5, 556 Purines, 8-lithiotrimethylsilyl-nucleosides alkylation, 5, 537 Purines, N-methyl-magnetic circular dichroism, 5, 523 Purines, methylthio-bromination, 5, 559 Purines, nitro-reactions, 5, 550, 551 Purines, oxo-alkylation, 5, 532 amination, 5, 557 dipole moments, 5, 522 H NMR, 5, 512 pJfa, 5, 524 reactions, 5, 556-557 with diazonium ions, 5, 538 reduction, 5, 541 thiation, 5, 557 Purines, oxohydro-IR spectra, 5, 518 Purines, selenoxo-synthesis, 5, 597 Purines, thio-acylation, 5, 559 alkylation, 5, 559 Purines, thioxo-acetylation, 5, 559... 

A benzyl carbonate was prepared in 83% yield from the sodium alkoxide of glycerol and benzyl chloroformate (20°, 24 h). It is cleaved by hydrogenolysis (H2/ Pd-C, EtOH, 20°, 2 h, 2 atm, 76% yield) and electrolytic reduction (-2.7 V, R4N X, DMF, 70% yield). A benzyl carbonate was used to protect the hy-droxyl group in lactic acid during a peptide synthesis. 

Certain functional groups may be protected from reduction by conversion to anions that resist reduction. Such anions include the alkoxides of allylic and benzylic alcohols, phenoxide ions, mercaptide ions, acetylide ions, ketone carbanions, and carboxylate ions. Except for the carboxylate, phenoxide, and mercaptide ions, these anions are sufficiently basic to be proton-ated by an alcohol, so they are useful for protective purposes only in the... 

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