Nitriles, addition phosphorylation

The addition products of MesSiCN 18 to carbonyl groups eliminate trimethylsilanol 4, in the presence of phosphoryl chloride in pyridine or of AICI3 in benzene, to give unsaturated nitriles. Thus ketone 1635 adds 18 and is subsequently converted, in a one-pot procedure, in 82% overall yield, into the olefin 1636 [27], whereas the adduct 1637 gives a mixture of the unsaturated nitriles 1638 [28] and ketone 1639 adds MesSiCN 18 and eliminates MesSiOH 4 or HMDSO 7, in one step, to give the a,y9-unsaturated nitrile 1640 [29] (Scheme 10.12). 

Phosphoryl substituted nitrile ylides have also been generated via the imidoyl chloride-base route using precursors 118 (R=Et, c-CeHn, f-Bu) prepared by the addition of an acid chloride to diethyl isocyanomethylphosphonate (120) (65). Treatment of the imidoyl chloride with triethylamine at —10 to 0 °C in the presence of dipolarophiles gave adducts in yields of up to 55% (e.g., 119 and 121) in ratios 1 4, 1 3 for R=Et and c = CgHn, respectively. 

Michael addition has been applied to the formation of cyclopropanic systems. Thus, the addition of phosphonate carbanions generated by LDA in THF, by NaH in THF, by thallium(I) ethoxide in refluxing THF, or by electrochemical technique to oc,P-unsaturated esters provides a preparation of substituted 2-(alkoxycarbonyl)cyclopropylphosphonates in moderate to good yields via a tandem Michael addition-cyclization sequence (Scheme 8.47). The cyclopropanation has also been achieved via oxidation with iodine in the presence of KF-AI2O3. Nitrile ylides prepared from acyl chlorides and diethyl isocyanomethylphosphonate in the presence of Et3N react with methyl acrylates by a 1,3-dipolar cycloaddition to give phosphoryl pyrrolines or pyrroles. ... 

The cycloaddition of an arylnitrile oxide to methyl ethynylmethylphosphinate in an inert solvent at 5 °C produces a (5) -phosphinoylated-isoxazole 513 in high yield " and phosphorylated 1,2,4-oxadiazoles 514 are obtainable in a similar addition to (R0)2P(Z)CN (Z = O or Phosphorylated nitrile oxides, e.g. 515, are generally prepared by the Et3N-dehydrobromination of the product from the bromination of the oxime of a j5-(dialkoxyphosphinoyl)acetaldehyde, and then used in situ in reactions with alkenes to give isoxazolines and with alkynes to give isoxazoles . The chlorination and subsequent dehydrochlorination of diethyl (nitromethyl)phosphonate yield the nitrile oxides 516 (R = EtO Pr O or morpholinyf and these, with unsaturated centres, yield isomerically phosphorylated isoxazolines and isoxazoles. 

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