Aminotroponeiminates

This work was initiated in 1988 when Villacorta et al.71a reported the asymmetric conjugate addition of a Grignard reagent to 2-cyclohexenone. This study showed that 1,4-adducts with 4-14% ee were obtained in the presence of aminotroponeimine copper complex.713 Enhanced results (74% ee) were obtained by adding HMPA or silyl halides.71b Several other copper complexes were also used for inducing asymmetric conjugate addition reactions. Moderate results were obtained in most cases when THF was used as the solvent and HMPA as the additive. 

Aminosulfur trifluorides, 19 192 syntheses and properties of, 14 347-348 Aminotroponeimines, 32 29 5-Aminouracil, astatination, 31 75 Aminousulfanuryl fluoride ions, 19 226,... 

I will mention one other case in which the metal is kept constant but the ligand is changed. In the aminotroponeimineate chelates (J) with 4-coordinate... 

Fig. 21. Spin density distribution in some nickel(II) aminotroponeimineates. [Benson et al. (4).]...

The first reaction of this type was reported by Lippard et al. in 1988 the reaction of 2-cyclo-hexenone (3) with Grignard reagents in the presence of the chiral aminotroponeimine copper complex 5 as catalyst gave the 1,4-adducts 4 with 4- 14 % ee [3a]. The selectivity was increased to 74 % ee by addition of hexamethyl-phosphoric triamide (HMPA) and silyl halides [3b]. 

Numerous aminotroponeimineate complexes of type e, with nickel (II), have been prepared and are found to undergo square planar-tetrahedral interconversion (27). Extensive nuclear magnetic resonance data have been accumulated on this system along with magnetic moment and electronic spectral measurements (27). 

The first epoch-making catalytic process was developed by using a chiral copper amide derived from an amine 16 in 1990. With 3 mol% of aminotroponeimine (16) and copper, butylmagnesium chloride reacted with cyclohexenone to afford the corre.sponding adduct in 74% ee (Eq. (12.20)) [45]. 

Owen and Thomley (547) have reviewed covalency in transition metal ions and, in particular, in nickel complexes. The NMR contact shift method has been used by Eaton et al. (195) to determine spin densities on organic ligands of paramagnetic molecules. In particular (194), a series of nickel aminotroponeiminates have been studied whereby conjugative and hyperconjugative effects within the molecule may be monitored. Similar studies of contact shifts have been carried out on Co and Ni pyrromethenes and porphyrins (196) and on many transition metal acetylacetonates (193) by Eaton et al. 

By reaction of 1,2-diethoxytropylium salts with amines and/or sodium hydrogen sulphide thiathiotropolone, aminothiotropones and aminotroponeimines may be prepared [343]... 

Methoxytroponeimine has been used similarly as a precursor for aminothiotropones and aminotroponeimines [344],... 

Of particular interest are the aminotroponeimines, which have also been prepared by the action of ammonia or amines on 5,5,6,6--tetrafluorocyclohepta-1,3-diene [345], and by the reaction between tropone and aniline or some p-substituted anilines in the presence of copper(II) acetate [346]... 

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