Phosphorodiamidites —

A series of alkyl phosphorodiamidites (77) has been prepared using standard methods. Their potential as coupling reagents in... 

Reactions Catalyzed by Iridium Complexes of DIAPHOX and Phosphorodiamidite Ligands... 

Scheme 7 Allylic etherification catalyzed by [Ir(COD)Cl]2 and a phosphorodiamidite ligand...

Example 32 Fraser-Reid and his associates in their synthetic approaches to lipidated phosphoglyceroinositides have introduced the phosphate backbone via phosphoroamidite method employing 0-benzyl-bis(]V,Ar-diisopro-pyl)phosphorodiamidite [66]. 

The thiophosphite (27) with acetyl chloride gave mainly the Arbuzov product (28) in methylene chloride, but the substitution product (29) was the main product in hexane or without solvent, probably because the intermediate is a phosphorane in the latter case. 2-Acetylphenyl alkylphosphonamidites, phosphorodiamidites, or phos-phoramidites (30) upon heating gave different cyclisation products (31)-(33) dependant on the substituents on phosphorus, and on the amount of amine hydrochlorides present in (30). ... 

Phosphorodiamidites, e.g. (48), and M-chloroamines (49) gave exclusively di-amidochloridates, e.g. (50), in methylene chloride, whereas in petroleum ether some amidate, e.g. (51), was formed as well. The reactions of carbon tetrachloride with alkylbis(dialkylamino)phosphines (52) have been further studied this year. The remarkable rearrangement (53) to (54) occurs only with large isopropyl substituents on nitrogen, and with alkyl or hydrogen on the ylidic carbon. 

Certain P-chiral phosphorodiamidite ligands (e.g., 30A, 30B) complex with iridium(I) to form catalysts for promoting reaction of cinnamyl methyl carbonate with ArOH to form chiral aryl a-vinylbenzyl ethers. ... 

Very high yields of alkyl phosphorodiamidites (48), or unsymmetrical dialkyl phosphoramidites (49), are realised by treatment of tris(dialkylamino)phosphines (50) with the stoichiometric amount of alcohol in the presence of catalytic amounts of iodine.Instead of iodine, a diethylammonium diethyldithio-carbamate/diethylamine catalyst also effects the selective transformation of (50, R = Et) to (48)A series of tris(dialkyl-amino)phosphines (51) has been prepared from tris(diethylamino)-phosphine by transamination no catalyst was added, and di-ethylamine was removed by pumping. 

Tris(hexafluoroisopropyl) phosphite (105) has been used to prepare ribonucleoside H-phosphonates (106), and deoxyribo-nucleoside phosphites (107) ° both were used as monomers to prepare oligonucleoside H-phosphonates on a solid support, with W-methylimidazole as catalyst for the coupling of (107). Several new alkyl phosphorodiamidites (108) and (109) have been used... 

Sal keeva et al. studied the reactions of ethyl and /-butyl phosphorodiamidites with chloroacetone, bromoacetone, and a-chloroethyl acetate. The reaction pathway is determined by the structure of the intermediate quasiphosphonium compound responsible for the formation of the Arbuzov products as well as for the occurrence of the anomalous reaction yielding vinyl phosphate (Perkow product).26 The yield of the Arbuzov product increases from chloroacetone to bromoacetone, because the anions of low basicity are more rapidly ionized, which facilitates the formation of the ionic form of the intermediate. Also /-butyl phosphorodiamidite forms via Arbuzov reaction as the major product, because the second stage of the S l reaction is accelerated.26... 

Diphenylacetylenes. In a recent synthesis of diphenylacetylenes, the phos-phorochloridite (1) was allowed to react with a benzyl alcohol in the presence of triethylamine to form a phosphorodiamidite (2). Reaction of (2) with a benzo-trichloride gave (3), which was converted into a diphenylacetylene (4) on dehydrochlorination. Diphenylacetylene itself was obtained in 62% overall yield ... 

Much attention has been devoted to the conversion of aldehydes into the trimethylsilyl ethers of (a-hydroxyalkyl)-phosphonic acids 210 or analogous -phosphinic acids, or of the corresponding (a-hydroxyalkyl)phosphonic diamides 211 by the use of dialkyl trimethylsilyl phosphite or Me3SiOP(NEt2)2 (or other phosphorodiamidite) It is a reaction which occurs very readily, even at room temperature, and the ready methanolytic or hydrolytic removal of the silyl protecting group makes the procedure an attractive alternative to the direct synthesis of the (a-hydroxyalkyl)phosphonic acids from dialkyl hydrogenphosphonates and carbonyl compounds. Silyl-protected hydroxy-phosphonic and -phosphinic acid derivatives are useful for further synthetic development. ... 

In 2009, P-chiral phosphorus triamide ligands were applied in Ni-catalyzed asymmetric hydrovinylation of styrene with promising results, good yields (77%), and good enantioselectivity (up to 63% ee). Recently, phosphoramidite and P-stereogenic phosphorodiamidite ligands L17 and L18 derived from (Sj-2-phenylamino-2 -hydroxy-l,l -binaphthyl (7y-Ph-NOBIN) and bis(l-phenyl-ethyl)amine were synthesized and applied in asymmetric hydrovinylation of styrene, leading to almost perfect selectivity and enantioselectivity (up to 91% ee) (Scheme 9.5). ... 

Scheme 9.5 NOBIN-based phosphoramidite and phosphorodiamidite ligands used in asymmetric Ni-catalyzed hydrovinylation.

Phosphinic acid hydrazides Phosphonic acid diamides Phosphorodiamidites... 

Reactions with phosphorodiamidites Replacement of chlorine by alkyl... 

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