Reactions of P(MeNCH2CH2)3N with primary, secondary, and tertiary alkyl halides: Evidence for a solvent-enhanced dehydrohalogenation

2,8,9-Tris(2-methylpropyl)-2,5,8,9-tetraaza-1λ5-phosphatricyclo[3.3.3.01,5]undecan-5-ium chloride dihydrate

“…Unlike proazaphosphatranes, their protonated phosphonium salts known as azaphosphatranes with the five-membered tricyclic frameworks exist as solid states. Even though a lot of azaphosphatranes have appeared in the literature, only few examples of their solid state structures have been reported (Kingston et al, 2005;Liu et al, 1999;Liu et al, 2000;Mohan et al, 1996;Thirupathi et al, 2003;Wroblewski et al, 1995). In addition, the similar structure of the title complex (I) with four chloroform molecules in the monoclinic unit was reported in the literature; however, no crystallographic data and parameters were provided (Kisanga et al, 2001).…”

Phosphorus‐Containing Superbases: Recent Progress in the Chemistry of Electron‐Abundant Phosphines and Phosphazenes

“…The phosphines of Verkade type are useful reagents in organic syntheses [63] and enable a large bandwidth of reactions under mild reaction conditions and acts as Lewis base catalyst for the trimerization of isocyanates to isocyanurates [64] or as Brønsted base for syntheses of important oxazoles and pyrroles, [65] as well as for monoalkylations [66] and dehydrohalogenation reactions. [67,68] Pro-azaphosphatranes have also found application as auxiliary bases in Michael addition [69] or 1,2-addition reactions. [70] Later, when Schwesinger's activities were focused on the preparation and investigation of strong bases with vinamidine structure as auxiliary bases in dehydrohalogenation reactions, [4,71,72] he observed the outstanding proton-accepting properties of amino-substituted phosphanimines and laid the foundation stone of the wide field of the so called "Schwesinger bases".…”

“…With a MeCN p K value of 32.9 for the methyl derivative 14 a , pro‐azaphosphatranes are of similar basicity as diphosphazenes (R 2 N) 3 P=N‐(R 2 N) 2 P=N t Bu ( 16 , Scheme 6), [60–62] which were published a few years later by Schwesinger. The phosphines of Verkade type are useful reagents in organic syntheses [63] and enable a large bandwidth of reactions under mild reaction conditions and acts as Lewis base catalyst for the trimerization of isocyanates to isocyanurates [64] or as Brønsted base for syntheses of important oxazoles and pyrroles, [65] as well as for monoalkylations [66] and dehydrohalogenation reactions [67,68] . Pro‐azaphosphatranes have also found application as auxiliary bases in Michael addition [69] or 1,2‐addition reactions [70] …”

“…The phosphines of Verkade type are useful reagents in organic syntheses [63] and enable a large bandwidth of reactions under mild reaction conditions and acts as Lewis base catalyst for the trimerization of isocyanates to isocyanurates [64] or as Brønsted base for syntheses of important oxazoles and pyrroles, [65] as well as for monoalkylations [66] and dehydrohalogenation reactions. [ 67 , 68 ] Pro‐azaphosphatranes have also found application as auxiliary bases in Michael addition [69] or 1,2‐addition reactions. [70] …”

“… [80] Moreover, the cyclic imine derivative is more basic than the acyclic compound. Although Verkade's bases 14 are capable in dehydrohalogenation reactions of secondary and tertiary alkyl halides,[ 67 , 68 ] a pronounced nucleophilicity of this base leads to alkylation with primary alkyl halides as well as an eager formation of coordination adducts with Lewis acids. [ 54 , 58 , 64 , 81 ] The good accessibility of the phosphorus atoms of the free bases also applies to the PH functions of the respective protonated forms, which suggests that Verkade's bases 14 cannot be employed for the realization of non‐coordinated or “naked” anions.…”