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Chiral Lithiated Phosphoric Triamides: Structure, Reactivity, and Salt Effects
Author(s) -
Müller Jürgen F. K.,
Zehnder Margareta,
Barbosa Frédérique,
Spingler Bernhard
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19990908)82:9<1486::aid-hlca1486>3.0.co;2-m
Subject(s) - chemistry , lithium (medication) , reactivity (psychology) , dimer , phosphoric acid , ion , medicinal chemistry , bicyclic molecule , monomer , salt (chemistry) , computational chemistry , ab initio , alcohol , stereochemistry , organic chemistry , medicine , alternative medicine , pathology , endocrinology , polymer
The theoretical structure of a cyclic phosphoric triamide 3 and of its monolithiated isomers 4 – 6 was calculated by ab initio methods ( Fig. 1 , Tables 1 and 2 ). The global minimum in 4 consists of a five‐membered Li−C−N−P−O chelate. The intermediates 5 and 6 are, relative to 4 , energetically unfavorable by 15 and 18 kcal mol −1 , respectively, due to distortion in order to accommodate the N‐complexation of the Li + ions. NMR Investigations ( 1 H, 13 C, 31 P, and 7 Li) of the lithiated bicyclic phosphoric triamide 1 were performed ( Tables 3 – 5 ). The lithium aminomethanide 2 is characterized by a sp 3 ‐hybridized anion supporting Li−C contacts. The anions exist in a monomer‐dimer equilibrium in solution ( Scheme 2 ). Trapping reactions of rac ‐ 2 with carbonyl compounds generated the corresponding amino‐alcohol derivatives with high diastereoselectivities ( Scheme 3 , Table 6 ). A rational for the stereochemical outcome is given ( Fig. 4 ). In the presence of LiBr, a P−N bond cleavage occurred on reaction of rac‐ 2 with aldehydes, which allowed the synthesis of (1‐hydroxylalkyl)phosphonic diamides ( Scheme 5 , Table 7 ).