Synthesis Of Proazaphosphatrane And Its Application

Proazaphosphatranes, also named Verkade Base, are exceedingly strong nonionic bases which facilitate reactions previously restricted to ionic bases such as NaH, potassium t-butoxide, LDA and NaHMPS. Organic transformations facilitated by proazaphosphatranes also tend to be more selective, which aids product purification. These transformations are also generally quite devoid of side reactions (which often accompany reactions of ionic bases) and so it is not uncommon for crude products to exceed 95% purity. Proazaphosphatranes can also be used as ligands to generate highly active catalysts in combination with metal complex catalysts such as Pd2(dba)3, Pd(OAc)2 and Pt(DVDS) because of their extraordinary electron-donating capability and relatively weak nucleophilicity.We document herein the improved synthesis of one kind of Proazaphosphatrane. Proazaphosphatrane both used as exceedingly strong nonionic bases and ligands in combination with metal complex catalysts are also described in this paper. The Pt(DVDS)/proazaphosphatrane complex was characterized by 31P NMR , while the structure of the products were confimed by 1H NMR , 13C NMR and GC-MS.The synthesis of tris(2-aminoethyl)amine(tren) from nitrilo-tris-propionamide via Hofmann Degradation is described. The nitrilo-tris-propionamide was prepared by the reaction of ammonia and acrylamide. The efficiency of sodium hypochlorite and sodium hypobromite used for Hofmann Degradation is also described in yield of 57.5% and 24.0% for each convertion. The synthesis of proazaphosphatranes is accomplished via agenerally short sequence of reactions that starts with tris(2-aminoethyl)amine which is converted into the corresponding mono-, di- or trialkylated tetramine which is then converted to an azaphosphatrane.Isomerization of allylaromatics, allyl phenylsulfide and methylene-interrupted dienes was accomplished by using proazaphosphatrane P(RNCH2CH2)3N as a non-ionic base in acetonitrile at 40°C. Allylaromatics were selectively isomerized to 1-arylpropene generally in >95% isolated yield with trans, cis ratios in the range of 85/15 to 96/4. Allyl phenylsulfide was converted to 1-phenylthiopropene (E/Z=57.7/42.3) in 93~95% yield. Allylimidazole was isomerized in 80~85% yield (E/Z=78.7/21.3). Methylene-interrupted dienes and linoleate derivatives can also be isomerized in high yield. Thus the proposed methodology offers significant advantages over existing methods, especially in terms of mild reaction condition, experimental simplicity and high conversion.The catalyst system Pt(DVDS)/Proazaphosphatrane, containing a bulky aminophospine ligand, catalyzes the hydrosilylation of various terminal alkynes with Et3SiH or Ph3SiH. These reactions occur efficiently and with high stereoselectivity. Anti-markonikov E-products or Markonikov alpha-products were obtained over 90% yields with the selectivity over 95%.