Phosphites polycyclic

Preparation of polycyclic ortho esters by the reaction of 1,2-hydroxy-benzene thionocarbonate with trimethyl phosphite [184, 185]. 

The [HP(NR)3] anion (R = 2-methoxyphenyl) can be regarded as an imido analog of phosphite [HPOs] and is obtained by lithiation of the reaction product between phosphoms trichloride and 2-methoxyanilme. The lithium salt is in fact a polycyclic cage compound. ... 

The formulations of the complexes herein reported, as shown in Tables IV-VII, are supported by the conductivity data reported in Table VII, as well as the analytical data in Table II. All of the complex species are diamagnetic (except those containing the [Co(N03)4] ion), as shown by the normal proton chemical shifts to be published later. The disproportionation reaction of Co(C104)2 with L reported previously to form [CoL5]C104 and [CoLe] (0164)3 (39) is similar to that reported for polycyclic phosphites (28). The strong-held nature of L in the cobalt (III) complex is demonstrated by the diamagnetism of the complex and a calculated Dq... 

The excellent reproducible analytical results for [NiLs](0164)2 cause substantial doubt to be cast on the formulation of the analogous polycyclic phosphite complexes as 6-coordinate 28). The relatively high molecular weights of the polycyclic phosphite nickel(II) complexes did not permit facile distinction between a 5 1 and 6 1 ligand-metal ratio on the basis of elemental analyses. Because the reflectance and solution spectral data in Table V are similar, it can be tentatively concluded that the [NiLs]" and [Ni(P(OCH)3(CH2)3)5] ions are essentially 5-coordinate in the solid and solution states. The absence of a band near 260 m/x in the case of the solu-... 

The rapid, acid-catalyzed hydrolysis of the polycyclic phosphite 2,8,9-trioxa-l-phosphaadamantane (L) produces two isomeric hydrolysates, 3-a-oxo-3-fi-hydrido-7-fi-hydroxy-2,4-dioxa-3-phosphahicyclo (3.3.1) nonane (Isomer A), and 3-fi-oxo-3-a-hydrido-7-ff-hydroxy-2,4-dioxa-3-phosphabicyclo (3.3.1) nonane (Isomer B), the configurations of which were tentatively postulated on the basis of infrared and PNMR spectra. Each isomer dehydrates to L under vacuum at 120°C., as well as in the presence of Cu+ or PhiC+ ions to give [CWLJ+ and [P/i3CL]+, respectively. With hydrated metal ions, L forms complexes of the general formula [M(L -HiO)A](X ), where X = BFa or ClOi and M = Mn+, Zn+, Fe+, and Cd+. Of the isomers, only A forms the identical complexes with these ions as well as Ni+. Infrared evidence is presented which is consistent with the postulate that L HiO is an enolform of A bound to the metal through phosphorus. 

Reaction of the benzoxazaphospholine 47 with the hydroxymethyl bicyclic phosphite 48 gave the polycyclic compound 51 by dimerisation of the intermediate 50. A similar reaction of 47 with pentamethylene diol (52) gave an unsymmetrical spirophosphorane (54) with a P-C bond via 53. ... 

Lewis acid catalyzed versions of [4 4- 2] cycloadditions are restricted to functionalized dieno-philes. Nonfunetionalized alkenes and alkynes cannot be activated with Lewis acids and in thermal [4 + 2] cycloadditions these suhstrates usually show low reactivity. It has been reported that intcrmolecular cycloaddition of unactivated alkynes to dienes can be accelerated with low-va-lent titanium, iron or rhodium catalysts via metal-mediated - -complex formation and subsequent reductive elimination39 44. Usually, however, low product selectivities are observed due to side reactions, such as aromatization, isomerization or oligomerization. More effective are nickel-catalyzed intramolecular [4 4- 2]-dienyne cycloadditions which were developed for the synthesis of polycycles containing 1.4-cyclohexadienes45. Thus, treatment of dienyne 1, derived from sorbic acid, with 10mol% of Ni(cod)2 and 30 mol % of tris(o-biphenyl) phosphite in tetrahydrofuran at room temperature affords bicyclic 1,4-dienes 2, via intramolecular [4 + 2] cycloaddition, with excellent yield and moderate to complete diastereocontrol by substituents attached to the substrate. The reaction is sensitive towards variation in the catalyst and the ligand. 

The product distribution depends on the nickel-phosphine ratio and the best yield of A (70% cis/trans = 19/1) is obtained when bisdiene is treated in toluene at 60 °C with llmol% Ni(COD)2 and 33mol% PhjP [124]. When a phosphite ligand is used, cyclohexene B or cyclopentane C derivatives are the major products. Functional groups such as esters, ketones, or ethers remain intact under the reaction conditions. The reaction is stereoselective and has been used for the synthesis of polycyclic natural products [125-128]. For example, the key intermediate for the enantioselective synthesis (-H)-asteriscanolide is obtained from a similar synthetic route [128]. The use of this strategy for the construction of a taxan skeleton has been briefly explored [129]. 

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