Diarylphosphinic acids, synthesis

A general and efficient method for the microwave-assisted synthesis of mono- and diarylphosphinic acids (579) and (581) from anihnium 7f-phosphinate (580) and aryl halides, using Pd(0) and Xantphos as a supporting ligand, has been developed by Stawihski and Kalek (Scheme A2)P The procedure was highly efficient and provided a rapid access to a broad spectrum of arylphosphinate derivatives. 

Cyanadons. Aluminum complexes of BINOLs (1) that are armed at C-3 and C-3 with diarylphosphine oxide groups possess both Lewis acid and base centers. Asymmetric cyanation of aldehydes and mines with MeaSiCN, and of quinolines and isoquinolines in a manner analogous to the Reissert reaction is successful (ee 70-90%). The asymmetric Strecker synthesis is applicable to conjugated aldimines and the higher reactivity of Me SiCN than HCN in the presence of 10 mol% of PhOH enables its use in catalytic amount while supplying stoichiometric HCN as the cyanide source. 

Synthesis and characterization of a new type of crown ethers (81)-(83) have been deseribed by Huszthy. The electronic circular dichroism (BCD) spectra of the ehiral crown ethers (i ,i )-(81) and (i ,i )-(82) eontaining an alkyl diarylphosphinate moiety, showed a strong exciton splitting in the Bb spectral region of the aromatic chromophores. In the case of the proton-ionizable ehiral derivative (i ,i )-(83) containing the phosphinic acid unit, the BCD speetrum measured in MeCN, suggested molecular dimerization or aggregation. 

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