Hydrides as reducing agents

Heterocyclic sulphoxides 65 mass spectra of 130-132 Hexahydronaphthalenols, synthesis of 310 Hofmann elimination 953 HOMO energies 1048, 1049 Homolytic substitution 1109 intramolecular 846 Horner-Wittig reaction 333 Hot electrons 892, 893 HSAB theory 282, 549 Hydrides, as reducing agents 934-941, 959 Hydrogen abstraction, photochemical 874, 876, 877, 879, 880... 

Towards Catalytic Relevance Bimetallic Activation of Acyl Ligands and Transition Organometallic Hydrides as Reducing Agents... 

Lithium aluminum hydride as reducing agent permits formation of alcohol 40 in the first step. This is then convened to iodide 41. Another reduction with a nucleophilic boron reagent produces an ethyl group at C-13 and thus structure 12. 

With lithium aluminum hydride as reducing agent in tetrahydrofuran, bis[4-inethoxyphenyl] dilellurium was obtained in 93% yield1. 

A. Hajos, Methoden Org. Chem. (Houhen-Weyl), 1981, IV/ld, 1. This is an excellent comprehensive review, entitled Metal Hydrides or Complex Hydrides as Reducing Agents , with many leading references and selected practical details (in German). 

The special characteristics of organotin hydrides as reducing agents are rationalized by the fact that the tin-hydrogen bond is both weaker and less polar than the B—H or A1—H bonds. These characteristics are manifested in reactions that proceed by either a free radical chain or polar mechanism, depending on the substrate, catalyst and reaction conditions. 

Various cyclopropanecarbonitriles have been converted to the corresponding cyclopro-panecarbaldehydes using diisopropylaluminum hydride, " - tri-hexylsilane, " lithium aluminum hydride, lithium diethoxyaluminum hydride, and lithium bis(2-methoxyethoxy)aluminum hydride as reducing agents. The yields were at best moderate. 

Dialkyl alanes, R2AIH, are now widely used in place of lithium aluminum hydride as reducing agents because they are particularly readily... 

Silylated 1,4-cyclohexadienes were used to replace tin hydride as reducing agents in radical chain reactions. They were prepared by TBDMSCl interception of the regioselec-tive metallation intermediate of cyclohexadienes, and subsequent methylation (eq 40). The 3-TBDMS-2,4-dimethoxy-l,4-cyclohexadiene was found to be a very efficient hydrogen donor reagent in various radical reactions. 

Sodium hydride as reducing agent 2-AcyI-l,2-dihydroisoquinoIines from isoquinolines... 

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