Hydrides, complex, reduction selective, with -, review

The main methods of reducing ketones to alcohols are (a) use of complex metal hydrides (b) use of alkali metals in alcohols or liquid ammonia or amines 221 (c) catalytic hydrogenation 14,217 (d) Meerwein-Ponndorf reduction.169,249 The reduction of organic compounds by complex metal hydrides, first reported in 1947,174 is a widely used technique. This chapter reviews first the main metal hydride reagents, their reactivities towards various functional groups and the conditions under which they are used to reduce ketones. The reduction of ketones by hydrides is then discussed under the headings of mechanism and stereochemistry, reduction of unsaturated ketones, and stereochemistry and selectivity of reduction of steroidal ketones. Finally reductions with the mixed hydride reagent of lithium aluminum hydride and aluminum chloride, with diborane and with iridium complexes, are briefly described. 

In the area of preparative chemistry, there are reviews of the functional-group selectivity of complex hydride reducing agents, the reduction of organic compounds with diborane, the formation of C—C bonds using organoboranes," and a report on the preparation, properties, and synthetic applications of catecholborane. ... 

The role of transition metal hydrides has been reviewed and a comparison between gas-phase, liquid-phase and electrochemical hydrogenation has appeared . Laser radiation of Fe(CO)s photocatalyses the gas phase hydrogenation of ethylene(10-70 C, 1-2.4 atm) with quantum yields up to 170 . Selective hydrogenation of dicyclopentadiene (1) to (2) without formation of (3) is achieved via the [RhCl(PPh3)3] catalysed reduction of complex (4) . The new hydride [ThHj(MegSiR2)] (R = Bu,... 

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