Diphenylphosphine, nucleophilic reactions

In the presence of a catalytic amount of methanethiolate-bridged diruthenium complex (la abbreviated as met-DIRUX), reactions of propargylic alcohols (2) with a variety of heteroatom-centered nucleophiles such as alcohols, thiols, amines, amides, and diphenylphosphine oxide gave the corresponding propargylic substituted... 

Diphenylphosphine oxide can be used as a phosphorus-centered nucleophile for propargylic substitution reactions, where its tautomer (diphenylphosphinous acid) is... 

The reaction of alkyl isothiocyanates, RNCS, with diphenylphosphinic hydrazide (338) in benzene has been reported.308 The bis(diethylamino)[(methylthio)thiocarbon-yl]carbenium salts (339 X = I or BF4) display ambident reactivity and can react either at carbenium carbon (hard nucleophiles) or at the thiocarbonyl sulfur atom (soft nucleophiles).309 Electrochemically generated superoxide reacts with dithioic S,S -diesters (dicarbothiolates) (340 Ar = C5H3N or C6H4) to give the monocarboxylate anions in 100% yield before giving the dicarboxylate anions.310... 

Allenes are activated by a diphenylphosphine oxide substituent towards nucleophilic substitution at the j3-carbon atom. Lithium dimethyl-cuprate adds quickly to the 1,2-bond to give, on hydrolysis, the olefin in 16-84% yield, according to the nature of the substituents (76). Optimum conditions were not reported. The intermediate a-copper compound resulting from the addition can be dimerized or reacted with methyl iodide [Eq. (106)]. Similar reactions involving methyllithium are complicated. 

Kende has demonstrated that the mixed anhydride from carboxylic acids and diphenylphosphinic chloride would acylate Grignard reagents to afford ketones in moderate to good yield. Tertiary carbinols were not observed unless excess Grignard reagent was added. The intermediate anhydrides were generally isolated and made free of triethylamine hydrochloride before addition of the nucleophile. The reaction shown in equation (52) gave improved yields over the simple addition of methyllithium to the carboxylic acid. ... 

Reactions.—Nucleophilic Attack on Carbon. Activated olefins and acetylenes. The full paper describing addition of P—H bonds to vinyl isocyanides has been published. The reaction of diphenylphosphine with vinyl isocyanide in the presence of base proceeds normally, whereas the corresponding reaction with phenylphosphine gave the 1,3-azaphosphole (24). 

Nucleophilic Attack at Other Atoms. - The chemistry of phosphine-borane adducts continues to develop. The diphenylphosphine-borane adduct has been employed in the synthesis of linear systems having a skeleton consisting of alternating phosphorus and boron atoms, e.g., (73). Unusual salt-like systems, e.g., (74), have been isolated from the reactions of trialkylphosphines with the dimethylsulphide adduct of dibromoborane. 

Similarly, activation of a coordinated alkene was suggested in Markovnikov-selective addition of diphenylphosphine to alkyl vinyl ethers promoted by Ni(II) and Pd(II) precatalysts such as NiBr2(PPh3)2. Nucleophilic attack on bound alkene, followed by loss of HX to form chelate 26 and protonolysis of the M-C bond would form the product and regenerate the catalyst (Scheme 34). This mechanism was consistent with the observation that added EtsN shut down the reaction [55, 56]. 

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