Epoxidation of the PC Double Bond of Phosphaalkene Complexes: X‐Ray Crystal Structure Analysis of a Stable Oxaphosphirane Complex

Abstract

structures 4 and 5 were erroneously assigned to the two substdnces.['I As the "N-NMR spectrum shows, 14 has two NH, groups and one further nitrogen atom, which is not reconcilable with structure 5. eO-N = C H -CH-NO: 15As has already been suggested,"] in the reaction of 1 with potassium cyanide and tetrabutylammonium chloride in nitromethane/water the condensation product 15['*] could be formed initiaIly. Possibly subsequent 0-alkylation by the sulfonate 1, nucleophilic attack by cyanide at the neighboring carbon atom and formal double elimination and addition of water (sequence variable) could lead to 9. D-8033 Martinsried (FRG) Angew. Chem. Int. Ed. Engl. 29 (1990) No. 10 8 VCH Verlagsgesellschafi mbH, 0-6940 Weinhelm, f990 0570-0833/9Oj1010-l167 X 3 . S 0 t .25/0 11 67

Phospha‐Organic Chemistry: Panorama and Perspectives

“…(14), (15)]. [8,46] Classical reactions of olefins, such as catalytic hydrogenation [47] and epoxidation [48] can only be achieved after [49] whereas hydrozirconation [50] leads to the P À H products [Eqs. (18) [2] Only some of the most significant cases will be treated here.…”

Quantum Chemical Calculations on CHOP Derivatives—Spanning the Chemical Space of Phosphinidenes, Phosphaketenes, Oxaphosphirenes, and COP− Isomers

“…Somewhat similar is the situation for strained ring systems containing phosphorus for which phosphiranes ( IV ) and 1 H -phosphirenes ( V ) [5] may serve as good cases in point. An existing synthetic challenge is represented by oxaphosphiranes ( VI ) [6,7], only experimentally described as a ligand in transition metal complexes, being valuable due to a high potential in polymer chemistry, and oxaphosphirenes ( VII ) [8,9] (a 3-phosphinyl-1 H -oxaphosphirene was computed as one of the possible CHOP isomers [10]) for which not even a (failed) attempt exists in the literature; the latter may stem from a (discouraging) degree of antiaromaticity [11]. The first stable derivative of a phosphaketene, possessing the general formula RP=C=O, was reported by Appel (R = Mes* = 2,4,6-tri- tert -butylphenyl) [12,13], and which remained the only derivative for a long time.…”

Epoxide-like Chemistry: 1,2-Bifunctional P-Ligands via Stereo- and Regioselective Ring Opening of an Oxaphosphirane Complex

“…Selective ring openings of oxiranes I (epoxides) represent the first step of polymerizations but can also yield important molecular building blocks such as ethylene glycol , or β-functional alcohols and, hence, are of paramount industrial importance. By comparison, ring-opening reactions of oxaphosphirane complexes II (Scheme ) have not been widely explored, although they largely mimic the chemistry of oxiranes and have become readily available via the effective, yet facile synthetic protocol using Li/Cl phosphinidenoid complexes. − Only a few examples of ring-opening reactions have been reported using strong Brønsted acids such as HOTf or superacids such as protonated toluene, leading to selective C–O bond cleavage and side-on P -OH alkylidene phosphonium complexes. In order to expand applications of oxaphosphiranes, we figured that development of a Li/Cl phosphinidenoid complex having a sterically less demanding P-substituent that is easy to access in combination with an appropriate carbonyl derivative could be key.…”