Stereochemical aspects of phosphorus‐containing cyclohexanes

The first structural study on a cyclic tricoordinate phosphorochloridite and a pentacoordinate phosphorane based on 1,2,3,5-protected myo-inositol—a new conformation of 1,3,2-dioxaphosphorinane ring

“…33 The P-O bond distances for apical substituents in TBP structures are expected to be longer than the equatorial ones. In compound 9, one of the P-O(apical) bonds [P-O(4) 1.6306 (14) Å ] is actually 0.02 Å shorter than P-O(equatorial) bonds [P-O(9) 1.6546(15) Å ]. Although one can say that O(4) is connected to an aliphatic residue and O(9) belongs to a 5-membered catecholate residue, the fact remains that apical one is shorter.…”

“…This is quite interesting because for the previously determined structures containing unconstrained phosphorinane rings, a chair conformation was found. [13][14][15][16][22][23][24][25] The unusual boat conformation found in 7 is probably formed because in the chair conformation the phosphorus (or chlorine) may have unfavorable steric interactions with O(7) or C(2)-H (see Fig. 1).…”

“…11-13 By contrast, such a ring in the precursor P(III) compounds adapts a chair conformation of type II. [13][14][15][16] Thus there is interest in pentacoordinate phosphorus compounds formed with biologically relevant molecules 17 is a subject in which we have been interested. [18][19][20] We were interested in systems with the (1,3,5) positions blocked so that (4,6) positions can be effectively utilized for phosphorylation.…”

6-Membered P-Heterocycles: Ring-Condensed 1,3,2-Diheterophosphorinane 2-Chalcogenides

“…Among them, particularly the tetracoordinate P(V) 1,3,2-dioxaphosphorinanes and 1,3,2-oxazaphosphorinanes have attracted considerable attention from both stereochemical and pharmacological aspects ( Fig. 1) [2][3][4][5][6][7]. The main aims of these studies were: (i) to clarify the mode of action of second-messenger cyclic nucleotides (e.g.…”

“…The main aims of these studies were: (i) to clarify the mode of action of second-messenger cyclic nucleotides (e.g. cAMP and cGMP), which contain a 1,3,2-dioxaphosphorinane moiety and play important roles in hormone action and cell communication [5,8]; (ii) to acquire more information on the biotransformations of the clinically widely used antitumour agent cyclophosphamide and its analogues, which contain a 1,3,2-oxazaphosphorinane ring, in order to develop compounds with improved action and to reveal certain structure-activity relationships [2,9]; (iii) to synthesise novel, potentially active 1,3,2-diheterophosphorinane derivatives [10][11][12][13]; and (iv) to investigate the unique conformational behaviour of differently substituted six-membered P-hetero rings [1][2][3][4][5][6][7]. In contrast to the 1,3,2-dioxa-and 1,3,2-oxazaphosphorinanes, the corresponding 1,3,2-diaza analogues have been less comprehensively studied, although their synthetic importance increased when 1,3,2-diazaphosphinane phosphoramides proved to be effective auxiliaries for the promotion of stereoselective carbon-carbon or carbonhydrogen bond-forming reactions [14].…”