Phosphoramidate anions reactions with

The reaction between phosphoramidate anions and C02, resulting in P—N bond fission, was first reported in the early 1960s the fate of the phosphorus-containing moiety was not described clearly, nor were any conclusions reached as to the stereochemistry of the reaction. The reaction of the anions (96) and (97) with C02 and CS2... 

Having established a very effective method for the synthesis of tricar-bonyl(T74-vinylketene)iron(0) complexes, Thomas has subsequently undertaken the most comprehensive study on the reactivity of these complexes to date. The reactions of 221 with phosphoramidate anions,90134 coordinating ligands such as phosphines3 and isonitriles,69,87,89,135,142,143 a variety of nucleophiles,86,89135142 phosphonoacetate anions,88,89 alkynes,108,109,144,145 and al-kenes146,147 have ah been investigated. Crucially, Thomas has also developed a method138 for the kinetic resolution of the vinylketene complexes (221) that ultimately yields enantiomerically pure samples of the complex. This... 

Let us first consider the reaction between vinylketene complexes and phosphoramidate anions.90,134 Deprotonation of the appropriate phos-phoramidate with Bu"Li affords the corresponding phosphoramidate anion (232.a-232.c), which undergoes a Wadsworth-Emmons type reaction on the ketene carbonyl to afford the ketenimine complexes 233. Ketenimine complexes may also be prepared by the thermolysis of the vinylketene complexes (221) with isonitriles (vide infra).69... 

Having explored the scope of this reaction, it was then possible to use an optically active phosphoramidate (232.d), derived from (5)-a-methyl-benzylamine, to perform a kinetic resolution procedure.134,138 Upon reaction of 221 with 0.5 equiv of the phosphoramidate anion 232.d, selective reaction with the 7 -isomer of 221 resulted in an enhancement in the proportion of 5-221 along with the expected ketenimine products (233). The absolute configuration of i -233.d was determined by X-ray crystallography, and thus all other absolute configurations assigned by comparison of CD and HPLC data.39,138... 

In the palladium-catalyzed allylic amination reaction, primary and secondary amines can be used as nucleophiles, whereas ammonia does not react. Therefore, many ammonia synthons have been developed, and a variety of protected primary allyl amines can now be prepared using azide, sulphonamide, phthalimide, di-f-butyl iminocarbonate ((Boc)2NLi), and dialkyl A-(rerr-butoxycarbonyl)phosphoramide anions as the nucleophile [20], An example of the use of ((Boc)2NLi) 30 as the amine nucleophile in the palladium-catalyzed allylic amination reaction is shown in Eq. (9). This reaction also illustrates the problem with the regioselectivity in the reaction as a mixture of the products 31-33 are obtained [21]. 

Preparation of phenyl-substituted silyl anion is a simple process either from chlorosilanes or disilanes (equation 15). Trimethylsilyl anions can he prepared from hexamethyldisi-lane by reaction with RM (RM=MeONa, MeLi ) in a strongly basic solvent such as HMPA (hexamethyl phosphoramide). 

Diethyl N-cyclohexylphosphoramidate allowed to react with NaH in 1,2-di-methoxyethane, and phenyl isocyanate added to the resulting phosphoramidate anion N-phenyl-N -cyclohexylcarbodiimide. Y 60%.— Phosphoramidates, which are readily available, provide convenient laboratory procedures for the prepn. of unsatd. nitrogen compounds such as imines, ketenimines, isocyanates, or isothiocyanates. F. reactions s. W. S. Wadsworth, Jr., and W. D. Emmons, Am. Soc. 64, 1316 (1962). 

In the reaction of the phenyl phosphoramidate anion 53 (R = Ph) with carbon dioxide only triphenyl isocyanurate is obtained because the generated phenyl isocyanate trimerizes under the reaction conditions. Also, from sodium diethyl A -alkoxy-phosphoramidate (R = OR) and carbon dioxide only 1,3,5-trialkoxyisocyanurates are obtained . 

The reaction of carbon disulfide with iminophosphoranes is quite general. In addition to trialkyl- and triaryliminophosphoranes also bisalkoxyalkyliminophosphoranes, trialkoxyiminophosphoranes , dimeric trichlorophosphazenes and phosphoramidate anions react similarly. Bisiminophosphoranes react with carbon disulfide to give diisothiocyanates which are used in the construction of macrocyclic carbodiimides". ... 

RATE COEFFICIENTS FOR REACTION OF THE MONO-ANION OF PHOSPHORAMIDIC ACID WITH VARIOUS BASES AT 25 °C ... 

In contrast to the anion of diethyl phosphoramidate or trifluoromethanesulfonamide, which cannot be cleanly monoalkylated, - the anion of trifluoroacetamide (100) was monoalkylated by alkyl halides or alkyl methanesulfonate. The resulting A -alkylamides (101) were converted into primary amines by alkaline hydrolysis or reduction (NuBHa Scheme 42). Various primary amines were prepared from (100) with primary alkyl iodides or methanesulfonate, benzyl and allyl halides, a-bromocarbonyl compounds and 2,4-dinitrochlorobenzene. However, competitive elimination is a serious side reaction for less reactive primary alkyl chlorides and secondary halides or methanesulfonate. The synthesis of secondary amines from (100) has also been reported. ... 

A new perspective was opened up recently when Denmark demonstrated diat with chirally modified phosphoryl-activated allenes an asymmetric induction could be effected. From easily generated allenyl phosphoramidates containing an optically active amino alcohol, the diastereomeric adducts (37) and (39) could be obtained by addition of dlyl alcohol. When the separated adducts were employed in the carb-anionic Claisen rearrangement, a remarkable asymmetric induction (90 10) could be achieved with preferential formation of the diastereomers (38) or (40) respectively, whereas in a thermal reaction no stereoselection was observed (Scheme 63). Another example of an asymmetric induction in Claisen rearrangements is reported by Welch. ... 

The laboratories of Stec (24) and the author (26-28) have reported that the nitrogen anions of phosphoramidates react with carbonyl compounds (benzalde-hyde or CO2) to incorporate an atom of oxygen bonded to phosphorus at the expense of the nitrogen substituent, and that this reaction proceeds with retention of configuration at phosphorus. This stereochemically useful reaction, known as the Wittig-Staudinger reaction, is not limited to carbonyl compounds but can also be used with thiocarbonyls or selenocarbonyls to produce chiral phospho-rothioates or phosphoroselenates with retention of configuration at phosphorus (27). The primary application of this reaction has been in the preparation of both... 

The conversion of ArN2 salts into ArH takes place in hexamethyl-phosphoramide (by a long radical chain process), and also by the use of the naphthalene anion radical CioHs" in THF. Alternatively, deamination of ArNH2 can be carried out with Bu ONO in DMF. Unsymmetrical biaryls can be formed in a phase-transfer reaction between the diazonium fluoroborate (in an arene solvent) and KOAc complexed with 18-crown-6 polyether. ° Meerwein aryl-ation of fluorinated olefins with ArN2 and copper(ii) halides has been described, but an alternative procedure for the overall addition of ArHal to an alkene involves the use of ArNH2, Bu ONO, and copper(ii) halides in acetone or... 

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