The Acid-Catalyzed Reaction of Triarylmethyl Azides with Triphenylphosphine<sup>1</sup>

Leffler, John E.; Honsberg, U.; Tsuno, Yuho; Forsblad, I.

doi:10.1021/jo01070a008

Cited by 34 publications

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“…The first step involves nucleophilic attack of the phosphine on the terminal nitrogen of the azide reactant 27 producing a triazo intermediate 61 . Although some intermediates of type 61 have been isolated, such compounds normally decompose rapidly through a four-membered transition state 62 to provide the phosphinimine product 52 , 53 or 57 , 58 with the expulsion of N 2 gas. It is postulated that due to steric hindrance, a four-membered cyclic transition state 62 is not easily attained upon reacting BINAP 51 or MeOBIPHEP 56 with sulfonyl azide 27 through intermediate 61 (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

A Simple Resolution Procedure Using the Staudinger Reaction for the Preparation of P-Stereogenic Phosphine Oxides

et al. 2001

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The resolution of a variety of (+/-)-P-stereogenic phosphines is achieved by exploiting the Staudinger reaction of a (+/-)-phosphine with enantiopure (1S,2R)-O-(tert-butyldimethylsilyl)isobornyl-10-sulfonyl azide. The resulting mixtures of diastereomeric phosphinimines are generally separable by fractional crystallization or flash chromatography. Subsequent acid-catalyzed hydrolysis provides the corresponding optically pure phosphine oxides in high yields.

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Section: Introductionmentioning

confidence: 99%

A Simple Resolution Procedure Using the Staudinger Reaction for the Preparation of P-Stereogenic Phosphine Oxides

et al. 2001

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“…The Staudinger reaction between trialkyl- or triarylphosphines and alkyl azides − is useful in synthesis. − The iminophosphorane product of the reaction (eq 1) is a phosphorus−nitrogen ylide, which reacts with appropriate acyl derivatives (eq 2) to yield an amide after hydrolysis. , The iminophosphorane is formed via a triazaphosphadiene intermediate, frequently isolated 1,11-21 and characterized by infrared spectroscopy 17,18 and X-ray crystallography. , We have confirmed that description by means of 1 H NMR, 31 P NMR, FT-IR, and UV−vis spectrometry. Approximate kinetics for the successive stages of the reaction are more easily and more precisely measured by these methods than through the rate of nitrogen evolution. ,, Azidobimanes (easily prepared from bromobimanes 25,26 ) were selected as reactants with the objective of creating fluorescent amides. The NMR results are the most important in elucidating the course of the reactions and are emphasized in our report…”

Section: Introductionmentioning

confidence: 99%

Sequence of Reactant Combination Alters the Course of the Staudinger Reaction of Azides with Acyl Derivatives. Bimanes. 30.

et al. 1996

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The Staudinger reaction of azides has now been followed by NMR and other spectroscopic techniques. syn-(Azidomethyl,methyl)(methyl,methyl)bimane (1) and Ph(3)P form a triazaphosphadiene intermediate 2 and then the bimane P-triphenyliminophosphorane 3. The iminophosphorane reacts with an acyl chloride to yield an iminophosphonium salt 4 which then forms the oxazaphosphetane 13. The latter undergoes an electrocyclic reversion to form the phosphine oxide and the chloroimines 7E and 7Z, the last being hydrolyzed to the (acylamido)bimane 6. This set of reactions constitutes the "iminophosphorane pathway". A significant diversion of the reaction path to an (N-alkylamino)phosphonium chloride 8 occurs through reaction of 4 with H(2)O present in the CDCl(3) and through reaction of 3 with HCl. A different azide (alpha-azido-o-xylene 1b) produces the (acylamido)-o-xylene as the sole product. A less sterically hindered phosphine (tri-2-furylphosphine) reacts more slowly to form the iminophosphorane 3a from the azidobimane 1. Reaction of the bimane P-tri-2-furyliminophosphorane with acyl chloride gives only the (acylamido)bimane 6. If the acyl chloride is mixed with 1, followed by addition of the Ph(3)P, the triazaphosphadiene adduct 5 is formed via the triazaphosphadiene. The adduct 5 is converted rapidly into a six-membered cyclic compound 11. The latter either loses nitrogen to yield 6 via 7Z and 7E and the phosphine oxide or loses chloride 10 through a novel chloride-induced elimination reaction from its protonated form. The change in procedure thus results in a dramatic change in the reaction pathway, a reaction set that constitutes the "triazaphosphadiene adduct pathway". In the case of alpha-azido-o-xylene, alpha-chloro-o-xylene (10b) is the only product. The reactions of the azides 1 or 1b with tri-2-furylphosphine also produce chlorides as the major products accompanied by some acetamido derivatives. The nucleophile-induced reaction explains a "surprising result" (formation of ester rather than amide) reported by Sahlberg et al. (Sahlberg, C.; Jackson, A. M.; Claesson, A. Acta Chem. Scand. 1988, B42, 556-562). The intramolecular "aza-Wittig" reaction may depend on the nucleophilicity of the triazaphosphadiene. A comprehensive mechanistic scheme for the Staudinger reaction of azides is conveniently divided into the following: (A) formation of the triazaphosphadiene (Scheme 1), (B) reactions of the triazaphosphadiene (Scheme 2), and (C) reactions via the iminophosphorane (Scheme 3). Some approximate kinetic parameters are reported for some of the reactions.

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“…[17] Moreover, some phosphazides have been reported to equilibrate in solution with their phosphane and azide counterparts. [18] We have obtained some experimental evidence that support, although not conclusively, the proposed mechanism.…”

Section: Abstract In Spanishmentioning

confidence: 81%

Tripod-Tripod Coupling of Triazides with Triphosphanes. The Synthesis, Characterization, and Stability in Solution of New Cage Compounds: Chiral Macrobicyclic Triphosphazides

et al. 1998

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Several examples of a new type of cage compound, chiral macrobicyclic triphosphazides 15, have been prepared by tripod ± tripod coupling of tris(2-azidobenzyl)amines with 1,1,1-tris[(diphenylphosphino)methyl]ethane (triphos). The structure determination of C 3 or pseudo-C 3 -symmetric compounds 15 revealed their propellerlike topology, which accounted for their chirality, the rare Z configuration of the three phosphazide units, and a new conformation of the triphos fragment. Compounds 15 decomposed in solution with a phosphane arm-off mechanism, to give rise to complex mixtures instead of the expected tri-l 5 -phosphazenes. The stability of 15 in solution was enhanced by the quaternization of the bridgehead nitrogen atom in the form of an N-oxide. Substituents either in the ortho position to the N termini of the phosphazide units or on the benzylic carbon atoms contributed to a decrease in the stability of macrobicycles 15, and in some cases even prevented their preparation.

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The Acid-Catalyzed Reaction of Triarylmethyl Azides with Triphenylphosphine¹

Cited by 34 publications

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A Simple Resolution Procedure Using the Staudinger Reaction for the Preparation of P-Stereogenic Phosphine Oxides

A Simple Resolution Procedure Using the Staudinger Reaction for the Preparation of P-Stereogenic Phosphine Oxides

Sequence of Reactant Combination Alters the Course of the Staudinger Reaction of Azides with Acyl Derivatives. Bimanes. 30.

Tripod-Tripod Coupling of Triazides with Triphosphanes. The Synthesis, Characterization, and Stability in Solution of New Cage Compounds: Chiral Macrobicyclic Triphosphazides

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The Acid-Catalyzed Reaction of Triarylmethyl Azides with Triphenylphosphine1

Cited by 34 publications

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A Simple Resolution Procedure Using the Staudinger Reaction for the Preparation of P-Stereogenic Phosphine Oxides

A Simple Resolution Procedure Using the Staudinger Reaction for the Preparation of P-Stereogenic Phosphine Oxides

Sequence of Reactant Combination Alters the Course of the Staudinger Reaction of Azides with Acyl Derivatives. Bimanes. 30.

Tripod-Tripod Coupling of Triazides with Triphosphanes. The Synthesis, Characterization, and Stability in Solution of New Cage Compounds: Chiral Macrobicyclic Triphosphazides

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The Acid-Catalyzed Reaction of Triarylmethyl Azides with Triphenylphosphine¹