Date of Award
Doctor of Philosophy
John G. Verkade
Compounds of the type ZP(RNCH2CH2)3N where Z = a lone pair are proving to be versatile reagents and catalysts for an ever increasing number of organic transformations. These properties stem from the extraordinary basicity and low nucleophilicity of the phosphorus atom when certain Z substituents induce the bridgehead nitrogen to transannulate (even partially) to the phosphorus.;In this work, several novel azaphosphatranes have been successfully synthesized and characterized, where R = a bulky group (R3Si) (1f-i, 1f and 2g in chapter 3), or a chiral group (5--7 in chapter 5). A stable polymer-based azaphosphatrane (4 in chapter 4) was also synthesized from a commercially available Merrifield resin. In addition, the synthesis of commercially available P(MeNCH2 CH2)3N (1 in chapter 1) was remarkably improved in terms of chemical cost, labor cost, yield, safety and preparation time.;It has been found that the cations HP(CH3NCH2CH 2)3N+, HP(HNCH2CH2) 3N+ and HP[N(polymer)CH2CH2)N(CH 2CH2NH)2+ (2, 3 and 4 in chapter 4) serve as efficient procatalysts for dehydrohalogenation of organic bromides using NaH as a inexpensive stoichiometric hydride source in CH3CN at room temperature; that compound 6 in chapter 5 is an efficient derivatizing agent for the direct determination of enantiomeric ratios of chiral azides by means of 31P and 1H NMR spectroscopy; that N(CH2CH2NMe)3P=O ( 3 in chapter 7) is an efficient catalyst in a mild procedure for the silylation of primary alcohols, secondary alcohols, hindered secondary alcohols and of hindered phenols, in the presence of t-butyldimethylsilyl chloride (TBDMSCl) and t-butyldiphenylsilyl chloride (TBDPSCl); and that P(MeNCH2CH2)3N (2a in chapter 8) functions as a highly selective reagent for providing epoxides with trans/cis ratios as high as 99/1.;Cation [O=P(i-PrNCH2CH2) 3CH3]+ (3 in chapter 6) features the longest distance between the bridgehead atoms (3.56 A) so far recorded for phosphatrane cages despite a non-tetrahedral CNbridgeheadC angle (~114°). The 70.8°NbridgeheadCCN torsion angles in the bridging moieties of 3 produce a substantial twist along the C3 axis of the structure that does not easily allow racemization of the cage.;Benzene is formed at room temperature under acidic conditions from the novel trisubstituted cyclohexane derivative 1 (in chapter 9). The dominant reaction in the decomposition of the isolable thermally stable Staudinger intermediate in the presence of HA is the formation of benzene, nitrogen and [H2N=PR3]A.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
Liu, Xiaodong, "New developments in azaphosphatrane systems ZP(RNCH2CH2)3N " (2000). Retrospective Theses and Dissertations. 1098.