Tetrahydrofuran adducts

This point is borne out by the structure of tris indenyl samarium (5d). An earlier report of the nmr spectrum was interpreted as evidence of covalent bonding in the tetrahydrofuran adduct of samarium triindenide 66). Indenyl anion. 

Few examples of carbonyl ylide additions to Cjq are knovm. A stable tetrahydrofurane adduct 272 (Scheme 4.47) has been prepared based on the generation of the ylide by thermal opening of tetracyanooxiran (TCNE oxide) 270 [316]. 

By crystallizing the stable silaethene from diethyl ether/THF we isolated - according to the X-ray structure determination - a tetrahydrofuran adduct (Scheme 6) [16]. This adduct, which could be transformed into the "naked" silaethene, represents the first example of base adducts of silenes which themselves play a central r61e in my following statements. 

Fluoroalkoxy Tellurium Trichlorides A mixture of 3 mmol of tellurium tetrakis[fluoroalkoxide] and 9 mmol of tellurium tetrachloride is refluxed in 20 ml of tetrahydrofuran for 3 h. The solvent is evaporated and the residue kept at 40 to 50°/0.03 torr for 2 h. The fluoroalkoxy tellurium trichlorides are isolated as the mono-tetrahydrofuran adducts that are stable below 50°. 

Table 9 Bond lengths (A) in tetrahydrofuran adducts of metal halides. ...

Asymmetric reduction of or y-functionalized alkyl aryl ketones provides a wide variety of chiral amino alcohols. Commercial -chloropropiophenone is reduced with borane-tetrahydrofuran adduct catalyzed by oxazaborolidine 45 to provide the chlorohydrin in over 99 % yield with 94 % ee. The resulting alcohol is a key intermediate for synthesis of the R form of fluoxetine (Prozac ), a serotonin-uptake inhibitor [53]. Using hydrogenation processes the functionalized amino ketones are converted directly into the respective products [8, 43e],... 

The base-free tris(indenyl) lanthanide(m) complexes (C9H7)3Ln (Ln = Nd, Pr, La) were prepared from the corresponding tetrahydrofuran adducts (C9H7)3Ln(THF). The strictly THF-free complexes are obtained when the... 

The tetrahydrofuran adduct, [/flc-W(CO)3(dppe)(thf)], can be prepared in a similar fashion, but the THF adduct is much less stable in the solid state than the acetone adduct. Complex 2 can be quantitatively converted to the THF adduct by dissolving 2 in THF. 

Pentaphenylborole (5) is a deeply colored solid, highly reactive both to air and toward alcohols. It forms colorless to pale yellow adducts with THF, pyridine, or benzonitrile. The H and C NMR spectra of the 1 1 borole-tetrahydrofuran adduct in CCL, the IR and UV spectra of the borole-pyridine adduct, and the IR spectrum of the borole-benzonitrile adduct have been recorded. 

A satd. soln. of benzhydryl isonitrile in tetrahydrofuran added with ice-cooling and stirring under Ng to triphenylborane in abs. tetrahydrofuran adduct (Y 73%) in tetrahydrofuran ice-cooled, stirred, and treated under Ng with an ethereal soln. of phenyllithium, abs. acetone added, and refluxed 0.5 hr. betaine (Y 83%). F. e. s. G. Bittner, H. Witte, and G. Hesse, A. 713, 1 (1968). 

C5H5)3Eu THF. The THF complexes exhibit a bathochromic shift in their color because of the coordination of the oxygen to the rare earth metal. Tetrahydrofurane adducts with 2 and 3 THF coordinated to the tricyclopentadienyl lanthanide complex are also known (Suleimanov et al., 1982c). 

Tris(indenyl) complexes of. some rare earths were prepared by Tsutsui and Gysling (1968,1969) by the reaction of the metal trichlorides with the sodium salt of indene. They are isolated as tetrahydrofuran adducts. The solvent-free tris(indenyl) samarium has been made by the interaction of samarium trichloride with bis(inde-... 

The supersilyl anions [4], (Fig. 2) work as excellent reaction partners. The tetrahydrofuran adduct NaR 2THF (4) of supersilyl sodium is easily prepared from supersilyl bromide and sodium in refluxing THF. It crystallizes in beautiful yellow needles which — according to the X-ray structure analysis — contain contact pairs of the molecule. On the other hand, the PMDTA adduct (5) of NaR and the benzene adduct 6 of KR form monomeric molecules in the crystals. Donor-free NaR (7) is dimeric, whereby silicon gains the coordination number 5, which is very unusual for supersilyl silicon. 

A soln. of 2,2,6,6-tetramethyl-4-cyano-l-oxa-2,6-disilacyclohexane in tetrahydro-furan added to a suspension of an intimate mixture of NaBH4 and quartz sand in abs. tetrahydropyran, BFg-tetrahydrofuran adduct then added drop-wise during ca. 0.5 hr., stirred and refluxed 1 hr. N,N, N"-tris-(2,2,6,6-tetra-methyl-l-oxa-2,6-disila-4-cyclohexylmethyl)borazine. Y 98%. W. Simmler, H. Niederprum, and H. Walz, B. 97, 1047 (1964). 

Allylation adducts of ( )-Y-(dimethylphenylsilyl)allylboronate 47 selectively undergo addition reactions with aldehydes. Lewis acid catalyzed [3 + 2] cycloaddition reaction of these allylsilanes with various aldehydes, e.g., 55, provides tetrahydrofuran adducts with high diastereoselectivity. ... 

The chemistry of 1-boraadamantane has been explored further. Triphenylphosphorus ylides react with the tetrahydrofuran adduct to give a stable compound which can be thermally rearranged to 4-alky1-3-borahomoadamantanes.Adducts of benzonitriles are formed in a similar way and these rearrange at 200 to the... 

Two of the early nitrogen derivatives of borane were NR3 -BHa and [(NH3)2BHJ][BH4 ]. These resulted, respectively, from symmetric cleavage of B2H6 (BH3 - -BH3) and unsymmetric cleavage of B2H6 (BHj + BH4). Many studies have shown that Lewis acid-base (BH3 base) products are common in borane chemistry due to the electron-deficient nature of boron. Phosphorus, arsenic, oxygen, and sulfur acid-base adducts are aU known. Borane (BH3) is commonly stored and marketed as its tetrahydrofuran adduct. 

Lewis acid catalyzed regioselective ring opening of a [2.2.1] bicyclic acetal with TMSOF occurs, furnishing a 2,5-disubstituted tetrahydrofuran adduct as a mixture of erythro and threo isomers (eq 16).3 ... 

Tetrahydro-2-furylsuccinic anhydride, MA-tetrahydrofuran adduct, 203 Tetrahydro-2-methyIfuran, MA radical adduct, 203 (Tetrahydro-2-methyl-2-furyl)succinic anhydride, MA-tetrahydro-2-methylfuran adduct, 203 Tetrahydronaphthalene, MA radical adduct, 198 l-(Tetrahydronaphthyl)succinic anhydride, MA-tetrahydronaphthlene adduct, 198 1,1,2,2-Tetrahydroperfluoroalkyl fumarate, grafting on polyethylene, 462 Tetrahydrophthalic anhydride MA copolymerization, 586 preparation, 15... 

Cydopropylbenzene is a good electron donor and, not surprisingly, yields triplet radical ion pairs with photoexcited CA. In dichloromethane, these intermediates lead to the spiro-tetrahydrofuran adduct 64 in 68% yield, but in acetonitrile, this drops to 5%. Both NQ and 2,3-dichloro-NQ react similarly with cyclopropylbenzene on irradiation and again the yields of adducts corresponding to 64 are very dependent on solvent polarity. 

In a similar economical process, dihydropyrans were obtained in good yields using Pd(OAc)2 and TDMPP (tris(2,6-dimethoxyphenyl)phosphine), through a 6-endo-dig cyclization process. The regioisomeric tetrahydrofuran adduct arising from 5-exo-dig cyclization was in some cases observed as minor product [102] (Scheme 52). 

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