Bis phosphinate derivatives

In the case of the bis phosphine derivatives of the group 7b metals, the lability of the oxygen atoms was so markedly retarded by substitution that it was necessary to enhance their reactivity by means of base catalysis (15, 14), a process having mechanistic features common wi Tx general base catalysis of the hydration of ketones (eq. 6) (15). 

The stability of the alkyl and aryl derivatives increases with the number of phosphines bound to nickel(II). The bis-phosphine derivatives can be prepared according to equations (144)-(146) and using organomagnesium halides or organolithium compounds.1224-1231 A tetrakis phosphine complex was obtained similarly (equation 147). 

Ruthenium(II) complexes may also be used to oxidize N-Boc hydroxylamine in the presence of tert-butylhydroperoxide (TBHP) to the corresponding nitroso dieno-phile, which is subsequently trapped by cyclohexa-1,3-diene to give the hetero Diels-Alder adduct (Entry 1, Scheme 10.26) [51]. A triphenylphosphine oxide-stabilized ruthenium(IV) oxo-complex was found to be the catalytically active species. Use of a chiral bidentate bis-phosphine-derived ruthenium ligand (BINAP or PROPHOS) result in very low asymmetric induction (8 and 11%) (Entry 2, Scheme 10.26). The low level of asymmetric induction is explained by the reaction conditions (in-situ oxidation) that failed to produce discrete, stable diastereomerically pure mthenium complexes. It is shown that ruthenium(II) salen complexes also catalyze the oxidation of N-Boc-hydroxylamine in the presence of TBHP, to give the N-Boc-nitroso compound which can be efficiently trapped with a range of dienes from cyclohepta-1,3-diene (1 h, r.t., CH2CI2, 71%) to 9,10-dimethylanthracene (96 h, r.t., CH2CI2,... 

BIS(PHOSPHINE) DERIVATIVES OF IRON PENTACARBONYL AND TETRACARBONYL (TRI-terr-BUTYLPHOSPHINE)IRON(O)... 

Bis(phosphine) derivatives of pentacarbonyliron are starting materials for the synthesis of several organometallic iron complexes. " Iron carbonyl phosphine complexes have attracted attention because of their relevance to photochemical catalysis of olefin hydrosilation. Though Fe(CO)3(PR3)2 complexes are used widely in organotransition metal chemistry, an efficient preparation of these compounds has not been reported. Clifford and Mukherjee describe two methods for the synthesis of tricarbonyl-bis(triphenyphosphine)iron(0). They report that direct reaction between Fe3(CO)j2 and triphenylphosphine in THF solvent gives a mixture of Fe(CO)3[P(C6Hs)3]2 (27%) and Fe(CO)4[P(C5H5)3] (34%). The second... 

Bis(phosphine) derivatives of pentacarbonyliron are starting materials for the synthesis of several organometallic iron complexes.Iron carbonyl phosphine complexes have attracted attention because of their relevance to... 

Since bis phosphine derivatives are found for a large number... 

The catalyst-free and catalyzed addition of >P(0)H species to allenyl-and alkynylphosphine oxide was investigated. The reaction of diphenyl-allenylphosphine oxide with Ph2P(X)H was performed without solvent and catalyst. In this case, the major product was the a-methylene-ethylene(bis-phosphine) derivative, while the methyl-vinyl(bisphosphine derivative) was... 

In a related strategy, ethynylphosphines (81) have been prepared with a view to synthesising polyphosphacyclopolyyne materials such as (82) (Scheme 24) [70]. Interaction between the phosphorus lone pairs and the organic 71-systems is supported by the fact that the phosphorus atoms of mono- and di-silyl-capped analogues of bis(arylphosphine) derivative (81) exhibit an unusually low inversion barrier (65 kj mol versus 130-140 kj mol for classical alkyl-or aryl-phosphines). Indeed, the rings (82) exhibit values of at ca. 300 nm, consistent with this assumption. 

The coordination chemistry of tertiary phosphine-functionalized calix[4]arenes have been described.279 Treatment of a bis(diphenylphosphino) or bis(dimethylphosphino) derivative of calix[4]arene with [PtCl2(COD)] leads to the formation of the corresponding dichloroplatinum(II) complex. The related diplatinum(II) species has also been reported with the tetrafunctionalized calix[4]arene.280 The mononuclear derivative is susceptible to oligomerization if the two free phosphine ligands are not oxidized or complexed to another metal center such as gold(I).279 The platinum(II) coordination chemistry of a mono-281 and diphosphite282 derived calix[ ]arene (n = 4 and 6, respectively) has also been described. 

Kang et al.6 reported a practical synthesis of an air-stable ferrocenyl bis-(phosphine) (p5, p5 )-l,l,-bis-(diphenylphosphino)-2,2 -di-3-pentyl ferrocene ([5, 5]-FerroPhos, 10a) and its application in the rhodium(I)-catalyzed enan-tioselective hydrogenation of dehydroamino acid derivatives. 

A fluorous version of the chiral bis-phosphine BINAP has been developed for asymmetric Heck reactions [5], Several fluorous-derivatized binaphthols and BINAP derivatives have been reported, (Scheme 10.4) [6], The silane spacer group present in one of the ligands was used to maximize the percentage fluorine on the molecule. Even so, the partition coefficient1 between FC-72 (see Chapter 3) and benzene was only 2.85, and not surprisingly, the reuse of the catalyst was poor. 

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