Exploring organic reactions using simple cyclodiphosphazanes

Phosphine-activated reactions of alkynes/alkenes/allenes as well as the Mitsunobu reaction involve a rich phosphorus chemistry. With the aid of simple cyclodiphosphazanes, characterization of many compounds analogous to the proposed intermediates in such reactions has been accomplished. Use of a cyclodiphosphazane in Pd-catalyzed N-arylation reactions is highlighted. Results on molecular non-stoichiometry in phosphorus compounds and on the use of chiral phosphorus systems are discussed. Synthesis of allenylphosphoramides involving a cyclodiphosphazane is also described. X-ray structures of the new compounds [(t-BuNH)(PhCH2CH(CN)CH2–)P(μ-N-t-Bu)2P(NH-t-Bu)]+[HCO3]− (13), [(t-BuNH)P(μ-N-t-Bu)2P(double bond; length as m-dashN-t-Bu)-C(double bond; length as m-dashCH2)CH(C6H4-4-Me)-P(O)(OCH2CMe2CH2O)] (18), [(i-PrNH)P(μ-N-t-Bu)2P(double bond; length as m-dashN-i-Pr)-N(CO2-i-Pr)-NH(CO2-i-Pr)] (24), [(S)-(2-OH-1-C10H6-1′-C10H6-2′-O-P(O)(NH-t-Bu)2] (36) and [(t-BuNH)(O)P(μ-N-t-Bu)2P(O)(CHdouble bond; length as m-dashCdouble bond; length as m-dashCMe2)] (40) are also reported.