Quinuclidine adduct

Fig. 5.10. The molecular structure of the quinuclidine adduct of Eu(DPM)3 (reprinted with permission from Bye,...

The proton chemical shifts for the fluorenyl carbanion (92, 129) are given in Table XII. Both FLi(DME)n in DME and FLi(THF)n in THF exist in solution as solvent-separated ion pairs (130, 131). This is consistent with the observation that the fluorenyl proton chemical shifts are nearly identical in these solvents. The 1 1 dimethoxyethane (DME) adduct in benzene probably has the same structural configuration as the 2 1 quinuclidine adduct (Figure 20) although a rapid equilibrium will... 

A gallane-quinuclidine adduct (compound 19) has been used as an alternative Ga source for the MOMBE growth of GaAs films. The surface decomposition of compound 19 is similar to the related alane adduct, [AlH3 NMe3 ] 7, and growth of GaAs is observed at much lower temperatures than those employed when Ga alkyl precursors are utilized. 

In 1991, the thermaUy robust quinuclidine adduct ofgaUane, quin-GaHs, was reported (which decomposes only at temperatures in excess of 100 and subsequently, the first cr-(GaH) complex was reported,... 

The molecular structure of the quinuclidine adduct of Eu(DPM)3 has been determined by Bye (1974). The coordination polyhedron is best described as a distorted octahedron formed by the six oxygen atoms with the nitrogen atom from the quinuclidine located above the center of one of the faces, yielding overall threefold symmetry (type a). 

Reactions of the iminophosphenium cation tosylate with an equimolar amount of quinuclidine or 2,2 -dipyridyl proceed almost instantaneously and quantitatively to a bis-coordinated adduct 19 [56] (Scheme 11). 

Preliminary mechanistic studies show no polymerization of the unsaturated aldehydes under Cinchona alkaloid catalysis, thereby indicating that the chiral tertiary amine catalyst does not act as a nucleophilic promoter, similar to Baylis-Hilhnan type reactions (Scheme 1). Rather, the quinuclidine nitrogen acts in a Brpnsted basic deprotonation-activation of various cychc and acyclic 1,3-dicarbonyl donors. The conjugate addition of the 1,3-dicarbonyl donors to a,(3-unsaturated aldehydes generated substrates with aU-carbon quaternary centers in excellent yields and stereoselectivities (Scheme 2) Utility of these aU-carbon quaternary adducts was demonstrated in the seven-step synthesis of (H-)-tanikolide 14, an antifungal metabolite. 

Molecular modeling of the reaction predicts attack of the CN" ion on the re face of the iV-allyl benzaldimine carbon to provide an (5)-adduct. The aromatic ring of the imine and the quinuclidine hydrogen bond stabilizes the iminium above the pyridazine, blocking the rear face of the imine bond. Nucleophilic attack by CN is... 

In the presence of thiourea catalyst 122, the authors converted various (hetero) aromatic and aliphatic trons-P-nitroalkenes with dimethyl malonate to the desired (S)-configured Michael adducts 1-8. The reaction occurred at low 122-loading (2-5 mol%) in toluene at -20 to 20 °C and furnished very good yields (88-95%) and ee values (75-99%) for the respective products (Scheme 6.120). The dependency of the catalytic efficiency and selectivity on both the presence of the (thio) urea functionality and the relative stereochemistry at the key stereogenic centers C8/C9 suggested bifunctional catalysis, that is, a quinuclidine-moiety-assisted generation of the deprotonated malonate nucleophile and its asymmetric addition to the (thio)urea-bound nitroalkene Michael acceptor [279]. 

Functionalization of the double bond of 2-azabicyclo[2.2.2]oct-5-ene derivatives has been shown to be remarkably regjoselective. Thus, oxymercuration [112] and selenohalogenation [113] lead to adducts which are convenient precursors of iso-quinuclidin-5-one and -6-one, respectively. This means an excellent control of the polarity at the double bond termini by the nitrogen atom (Note that simple allylic urethanes also undergo regioselective oxymercuration). 

Similar to other tertiary aliphatic amines, quinuclidine easily forms salts with mineral and organic acids, and quaternary derivatives with alkyl halides. However, the rates of reaction of alkyl iodides with quinuclidine are significantly higher than with tertiary aliphatic amines.32 For example, quinuclidine reacts with methyl iodide 50 times faster, and with isopropyl iodide 700 times faster, than does triethylamine. The addition compound of trimethylborane with quinuclidine is more stable than the corresponding adducts of tri-alkylamines. These results can be explained by the almost total... 

In the presence of a strong base, such as Dabco or quinuclidine, the reaction of 1,3,5-trinitrobenzene with anilines in DMSO yields anionic adducts (9) as shown in Scheme 1. Kinetic studies show that due to the instability of the zwitterionic intermediates, (8), values of k i are high, leading to the condition k kB[B], so that the proton transfer step, kB, is rate limiting in the overall reaction. In the corresponding reactions of 4-nitrobenzofuroxan, which form the adducts (10), the slower interconversion of parent molecules and zwitterions, due to a higher intrinsic barrier, leads to the condition k x kB[B], so that proton transfer is only partially rate limiting 49... 

Gallane-tertiary amine or -tertiary phosphine adducts 106, L-GaH3 (L = Me3N, quinuclidine, ( -G6Hn)3P), reduce a carbonyl group and other unsaturated functional groups. The selectivities are different to those observed for similar alane... 

The adducts of (Me3Si)3H2CjLi with the nitrogen bases quinuclidine [N(CH2CH2)3CH], tetramethylethylenediamine (tmeda, Me2NCH2CH2N-Me2), and pentamethyldiethylenetriamine [pmdeta, Me2NCH2CH2N-... 

The X-ray crystal structures of the quinuclidine and hexamethylenetetramine adducts show very long Os—N bonds (2.37 and 2.42 A respectively) while the symmetry of the 0s04 unit is little disturbed the Os—O bond lengths are between 1.697 and 1.722 A, and the O(axial)Os0(equatorial) angle of 100.6° is close to the tetrahedral angle of 109-47° (Figure 33).634... 

The oxide gives very stable tbp adducts with a variety of amines like pyridine or quinuclidine. It also forms highly colored but weak complexes with arenes.101 This has been exploited102 to convert benzene to polycyclohexane derivatives. 

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