Phosphorus compounds, reducing agents

Common reducing agents are hydrogen in the presence of metallic or complex catalysts (e.g. Ni, Pd, Pt, Ru, Rh), hydrides (e.g. alanes, boranes, LIAIH, NaBHJ, reducing metals (e.g. Li, Na, Mg, Ca, Zn), and low-valent compounds of nitrogen (e.g. NjHj, NjHJ, phosphorus (e.g. triethyl phosphite, triphenyiphosphine), and sulfur (e.g. HO-CHj-SOjNa = SFS, sodium dithionite = Na S O. ... 

In further modifications of these norprogestins, reaction of norethindrone with acetic anhydride in the presence of p-toluene-sulfonic acid, followed by hydrolysis of the first-formed enol acetate, affords norethindrone acetate (41). This in turn affords, on reaction with excess cyclopentanol in the presence of phosphorus pentoxide, the 3-cyclopentyl enol ether (42) the progestational component of Riglovic . Reduction of norethindrone affords the 3,17-diol. The 33-hydroxy compound is the desired product since reactions at 3 do not show nearly the stereoselectivity of those at 17 by virtue of the relative lack of stereo-directing proximate substituents, the formation of the desired isomer is engendered by use of a bulky reducing agent, lithium aluminum-tri-t-butoxide. Acetylation of the 33,173-diol iffords ethynodiol diacetate, one of the most potent oral proves tins (44). ... 

Pheromones, synthesis of 763, 767, 837, 958 Phosphorus compounds, as reducing agents 927, 928... 

The phosphorus atom in hypophosphorus acid is in the lowest oxidation state, + 1. The compound is, therefore, a powerful reducing agent. It combines readily and often explosively with oxidizing agents. For example, the acid reduces mercury(II) nitrate or mercury(II) oxide into mercury metal violently. 

Reactions with reducing agents can be explosive. The compound attacks most metals almost as vigorously as fluorine. It spontaneously ignites boron, silicon, phosphorus, arsenic, antimony, and iodine at ordinary temperatures. 

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