Reactions of N-phenyl-N-trimethylsilylamido esters of pentavalent phosphorus acids with electrophilic reagents

31P nmr has been used to show that, in MeNO2, M(SbF6)2 (M = Sn or Pb) forms 1:1 complexes with Ph2P(CH2)2PPh2, PhP[(CH2)2PPh2]2, MeC(CH2PPh2)3, [Formula: see text][Formula: see text]P[(CH2)2PPh2]3, and Ph2P[(CH2)2PPh]2(CH2)2PPh2. The phosphonium ligands are formed in situ. Spectra characteristics of slow inter- and intramolecular exchange were obtained in all cases except, perhaps, those involving the last two ligands, which may be involved in rapid intramolecular exchange. For the first five ligands, the maximum denticity is achieved and unambiguous one-bond M(II)—31P (M = 117/119Sn or 207Pb) coupling constants are reported and discussed. In the presence of M(SbF6)2 (M = Sn or Pb). PPh3 is protonated in MeNO2, while in acetone Sn(SbF6)2 forms a 1:1 complex with PPh3 which appears to be solvent-inserted, [Sn—O—CMe2PPh3]2+.Reduced temperature 31P nmr spectroscopy has allowed the detection of 1:2 and 1:3 (M:L) complexes of OPPh3, and 1:1 complexes of Ph2P(O)(CH2)2P(O)Ph2, PhP(O)[(CH2)2P(O)Ph2]2, and (O)P[(CH2)2P(O)Ph2]3, with both tin(II) and lead(II). The 1:1 complexes with polydentate ligands are isolable; nmr shows that the maximum denticity occurs except with the last ligand which behaves in a tridentate manner. Several two-bond M—O—P coupling constants have been obtained. Also, the changes which complexation produces in the P—P couplings are compared with changes produced in the analogous phosphine complexes.The synthesis and characterization of Ph2P(E)[(CH2)2P(E)Ph]2(CH2)2P(E)Ph2 (E = S or Se) and (Se)P[(CH2)2P(Se)Ph2]3 are reported. The 31P nmr spectra of these compounds are compared with those of the parent tetraphosphines and other members of the corresponding tetraoxide–tetrachalcogenide series.

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“…refs. [35][36][37]." We are presently extending our studies of acetone-inserted metal phosphine complexes.…”

Section: Attempts To Prepare Complexes With Monodentatementioning

confidence: 99%

A ³¹P nmr spectroscopic study of complexation of tin(II) and lead(II) by some phosphines, phosphine oxides, and related ligands, with the ³¹P nuclear magnetic resonance spectra of two tetratertiary phosphine tetraoxides and the analogous tetra-sulfides and -selenides

Dean¹,

Phillips²,

Polensek³

1981

Can. J. Chem.

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“…The reactions of aldehydes and ketones with acyl phosphites is reported for the preparation of a-acetyloxyphosphonates at 120 °C to produce the desired products in low yields. 3 The other reported procedures for this purpose include direct acetylation of…”

mentioning

confidence: 99%

Copper Triflate as a Useful Catalyst for the High-Yielding Preparation of α-Acetyloxyphosphonates under Solvent-Free Conditions

Firouzabadi¹,

Iranpoor²,

Sobhani³

et al. 2004

Synthesis

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A high-yielding and convenient procedure for the efficient conversion of a-hydroxyphosphonates to a-acetyloxyphosphonates using acetic anhydride in the presence of catalytic amounts of copper triflate is described.a-Acetyloxyphosphonates are considered as important and valuable phosphorus compounds for the synthesis of optically active a-hydroxyphosphonates. Enzymatic systems have been introduced for the enantioselective hydrolysis of racemic a-acetyloxyphosphonates. 1 Chiral and nonracemic a-hydroxyphosphonates are useful precursors for a variety of a-substituted phosphonates especially for a-aminophosphonic acids which have received considerable attention in medical, bioorganic and organic chemistry owing to their potential activities as analogues of aamino acids. 1a,2Literature survey indicates that a practical and high yielding method for the synthesis of pure a-acetyloxyphosphonates is rare. The reactions of aldehydes and ketones with acyl phosphites is reported for the preparation of a-acetyloxyphosphonates at 120 °C to produce the desired products in low yields. 3 The other reported procedures for this purpose include direct acetylation of ahydroxyphosphonates 4 with ketene catalyzed by BF 3 ·Et 2 O 5 or H 2 SO 4 . 6 These protocols suffer from usually low yields 5 , requiring rather high temperatures (70-80 °C) and long reaction times (10-15 h). 6 Acetylation of a-hydroxyphosphonates with Ac 2 O or AcCl in the presence of Et 3 N or pyridine has been conducted at room temperature in 1-18 hours resulting in low to excellent yields. 1b,1c,7 In the other reported procedure, AcCl has been used for direct acetylation of a-trimethylsilyloxyphosphonates at a rather high temperature (120 °C) to produce a-acetyloxyphosphonates in moderate yields (55-70%). 8 In this article we present a new procedure in which a mild Lewis acid, copper triflate [Cu(OTf) 2 ] 9 has been used for the first time for direct acetylation of a-hydroxyphosphonates with Ac 2 O at room temperature in the absence of solvent in excellent yields with short reaction times. Reactions of diethyl a-hydroxyphosphonates have been under investigation in our laboratory in recent years. 10 Along this line, recently we have introduced [Cu(OTf) 2 ] as a mild and efficient catalyst for the silylation of a-hydroxyphosphonates with HMDS. 10d A recent report on the acetylation of traditional hydroxy functional groups with Ac 2 O catalyzed by Cu(OTf) 2 11 prompted us to apply this Lewis acid catalyst for direct acetylation of diethyl a-hydroxyphosphonates. We have studied the reactions of various diethyl a-hydroxyphosphonates 1a-o in the presence of Ac 2 O catalyzed by 0.013-0.08 equivalents of Cu(OTf) 2 in the absence of solvent at room temperature (Scheme 1 and Table 1). Scheme 1As shown in Table 1, various types of diethyl a-hydroxy(arylmethyl)phosphonates 1a-k were cleanly converted into their corresponding diethyl aacetyloxyphosphonates 2a-k in excellent yields (92-98%). Diethyl a-hydroxy-2-naphthyl-, 3-pyridyl-, alkyland aryl-b,g-unsaturated phosphonates ...

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Reactions of N-phenyl-N-trimethylsilylamido esters of pentavalent phosphorus acids with electrophilic reagents

Cited by 2 publications

References 1 publication

A ³¹P nmr spectroscopic study of complexation of tin(II) and lead(II) by some phosphines, phosphine oxides, and related ligands, with the ³¹P nuclear magnetic resonance spectra of two tetratertiary phosphine tetraoxides and the analogous tetra-sulfides and -selenides

A ³¹P nmr spectroscopic study of complexation of tin(II) and lead(II) by some phosphines, phosphine oxides, and related ligands, with the ³¹P nuclear magnetic resonance spectra of two tetratertiary phosphine tetraoxides and the analogous tetra-sulfides and -selenides

Copper Triflate as a Useful Catalyst for the High-Yielding Preparation of α-Acetyloxyphosphonates under Solvent-Free Conditions

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Reactions of N-phenyl-N-trimethylsilylamido esters of pentavalent phosphorus acids with electrophilic reagents

Cited by 2 publications

References 1 publication

A 31P nmr spectroscopic study of complexation of tin(II) and lead(II) by some phosphines, phosphine oxides, and related ligands, with the 31P nuclear magnetic resonance spectra of two tetratertiary phosphine tetraoxides and the analogous tetra-sulfides and -selenides

A 31P nmr spectroscopic study of complexation of tin(II) and lead(II) by some phosphines, phosphine oxides, and related ligands, with the 31P nuclear magnetic resonance spectra of two tetratertiary phosphine tetraoxides and the analogous tetra-sulfides and -selenides

Copper Triflate as a Useful Catalyst for the High-Yielding Preparation of α-Acetyloxyphosphonates under Solvent-Free Conditions

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A ³¹P nmr spectroscopic study of complexation of tin(II) and lead(II) by some phosphines, phosphine oxides, and related ligands, with the ³¹P nuclear magnetic resonance spectra of two tetratertiary phosphine tetraoxides and the analogous tetra-sulfides and -selenides

A ³¹P nmr spectroscopic study of complexation of tin(II) and lead(II) by some phosphines, phosphine oxides, and related ligands, with the ³¹P nuclear magnetic resonance spectra of two tetratertiary phosphine tetraoxides and the analogous tetra-sulfides and -selenides