Grignard reagents, reactions with arsinates

E = As, Sb or Bi) react similarly with Grignard reagents, providing routes to cyclic arsines, stibines and bismuthines. Leung s group has reported further applications of asymmetric Diels-Alder cyclisation reactions in phosphine synthesis. A platinum complex chiral auxiliary has been used to promote the asymmetric [4-1-2] Diels-Alder addition of diphenyl(vinyl)-phosphine to 3-diphenylphosphinofuran, giving the eradocycloadduct (70) as the predominant stereoisomer. Related cycloadditions between 3,4-dimethyl-1 -phenylphosphole and ester-functionalised allylic phosphines have provided chemoselective routes to optically-pure P-chiral 1,2- and... 

These compounds (92) are prepared by the reaction of the dibromoethyl material (91) with either the disodium salt (43JCS547) or the di-Grignard reagent (50JCS1917) derived from a monoalkyl- or monoaryl-arsine with best yields reported from the latter route (Scheme 19). 

A still better synthesis for such spiroarsoranes was finally found in the reaction of the bis-2,2 -biphenylylenearsonium ion 120 (5,5 -spirobi[5f7-dibenzarsolium]) with a variety of organyllithium or Grignard reagents 121 123>, 120 being readily accessible from appropriate chlorinated arsine precursors 119a, b 121). 

The association of the amine hydrochloride with the aminoarsine complicates the purification of the aminoarsine. When aminolysis of the arsenic trihalide is followed by alkylation of the mono- or bisaminohaloarsine with a Grignard reagent to synthesize the aminoalkyl(or aryl)arsine, the stoichiometry of the reaction must be carefully controlled to avoid cleavage of the As N bond and formation of the tertiary arsine (see Section 2.1). A recent study has shown that the highest yields are obtained from the transamination... 

The optically active arsine sulphides 115, 119 and 121 (Table 8) were prepared by reactions between appropriate menthyl esters of thioarsinic acids and Grignard or alkyllithium reagents, which proceed with inversion of configuration at the arsenic(V) stereocentre. 

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