Alkaline hydrolysis of 1-alkoxy-2,2,3,4,4-pentamethylphosphetanium salts. Unusual order of ligand kinetic axiophilicities

Synthesis and Properties of Phosphetanes

“…The order Cl ∼ SMe > ArO ∼ i-PrO ∼ EtO ∼ MeO . NMe 2 > alkyl > vinyl ∼ aryl was derived from eq 41 122,146 in conjunction with results from other studies. 123,[147][148][149] It is noteworthy that alkaline hydrolysis rates for cyclic phosphonium salts increase significantly upon moving from large ring or acyclic compounds to smaller ring compounds.…”

“…The apicophilicity − of the phosphorus substituents constitutes one of the most important factors governing the relative stability of different isomers. Initially, the apicophilicity of a given substituent was seen as a function of its electronegativity, with more electronegative groups being more apicophilic (see ref and references therein).…”

Preparation of the Enantiomers of Compounds Containing Chiral Phosphorus Centers

“…The leaving group must depart by Berry pseudorotation (13) before ligand reorganization or turnstile mechanisms (186) can operate. Otherwise, ligand reorganization occurs, resulting in retention of configuration (76,79,35,167). The TBP concept (53,186,192) also explains retention of configuration, as shown in Scheme 3b.…”

“…Both a,b pairs can be readily separated (29). It o .0Et I S Me s (35) has been suggested that 112a hydrolysis involves elimination-addition with an intermediate such as 123 [reaction (36)]. The stereospecific P-O bond cleavage of 112a by ethoxide is distinct from stereospecific P-N bond cleavage of 107a by ethoxide.…”

“…Sele- The conversion of 112a to 120 occurs with net retention of phosphorus configuration. Reaction (35) can be explained if 117a is recyclized to 107a, which then slowly hydrolyses by a nucleophilic displacement mechanism. Furthermore, when a 112a-ethoxide solution is stored for several hours, the product mixture is that derived from P-N bond cleavage [reaction (35)].…”