The possible number of chiral and achiral tetrasubstituted [2.2]paracyclophanes possessing different types of symmetry (C(2), C(i), C(s), C(2v), C(2h)) is evaluated and a unified independent trivial naming descriptor system is introduced. The reactivity and regioselectivity of the electrophilic substitution of the chiral pseudo-meta- and achiral pseudo-para-disubstituted [2.2]paracyclophanes are investigated in an approach suggested to be general for the synthesis of bis-bifunctional [2.2]paracyclophanes. The mono- and diacylation of chiral pseudo-meta-dihydroxy[2.2]paracyclophane 14 with acetylchloride occur ortho-regioselectively to produce tri- 22, 23 and symmetrically 21 tetrasubstituted acyl derivatives. The same reaction with benzoylchloride is neither regio-, nor chemoselective, and gives rise to a mixture of ortho-/para-, mono-/diacylated compounds 27-31. The double acylation of pseudo-meta-dimethoxy[2.2]paracyclophane 18 is completely para-regioselective. Electrophilic substitution of pseudo-meta-bis(methoxycarbonyl)[2.2]paracyclophane 20 regioselectively generates the pseudo-gem-substitution pattern. Formylation of this substrate produces the monocarbonyl derivatives 35 only, whereas the Fe-catalyzed bromination may be directed towards mono- 36 or disubstitution 37 products chemoselectively by varying the reactions conditions. The diacylation and dibromination reactions of the respective achiral diphenol 12 and bis(methoxycarbonyl) 40 derivatives of the pseudo-para-structure retain regioselectivities which are characteristic for their pseudo-meta-regioisomers. Imino ligands 26, 25, and 39, which were obtained from monoacyl- 22 and diacyldihydroxy[2.2]paracyclophanes 21, 38, are tested as chiral ligands in stereoselective Et(2)Zn addition to benzaldehyde producing 1-phenylpropanol with ee values up to 76 %.

Two useful approaches to ortho-acylhydroxy[2.2]paracyclophanes, starting from 4-hydroxy[2.2]paracyclophane, have been developed. TiCl 4 -catalyzed Fries rearrangement and direct acylation occur regioselectively (to the ortho position with respect to the hydroxy group), leading to 4-acetyl-5-hydroxy[2.2]paracyclophane (3) and 4-benzoyl-5-hydroxy[2.2]-[a] A. N. Nesmeyanov Institute of Organoelement Compounds, 3295 paracyclophane (4) in high to excellent chemical yields. For compound 4, an X-ray investigation has been performed. ortho-Acylhydroxy[2.2]paracyclophanes 3 and 4 have been obtained in enantiomerically enriched forms (ee 92−99%) and the absolute configurations of their enantiomers have been determined. parative routes to enantiomerically enriched ortho-acylhydroxy[2.2]paracyclophanes were elaborated.

nitriles nitriles (benzene compounds) Q 0520 -125Asymmetric Trimethylsilylcyanation of Benzaldehyde Catalyzed by (Salen)Ti(IV) Complexes Derived from (R)-and/or (S)-4-Hydroxy-5-formyl[2.2]paracyclophane and Diamines.-A method for the catalytic, asymmetric preparation of cyanohydrins, versatile intermediates in organic synthesis, is presented using enantiomerically pure, cyclophane-based (salen)Ti(IV) complexes as catalysts. -(BELOKON, Y.; MOSCALENKO, M.; IKONNIKOV, N.; YASHKINA, L.; ANTONOV, D.; VORONTSOV, E.; ROZENBERG, V.; Tetrahedron

903-919.[13] The simulations for 1 were performed according to the published procedure [12] with a temperature parameter of 303 K and 2 x lo6 macro steps. Maximum step lengths were 20" ($), 20" ($). 25' (w), and 2.5" (T = C1'-01'-C6), leading to an overall acceptance ratio of 0.48. Five minima could be identified:minimum A, E,., = 0.00 kcalmol-'); r#J = 49", $ =124'. m = -80" (minimum B, E,., = 0.20 kcalmol-I); = 55", $ =149". 0) = -61" (minimum C, E,,, = 0.56 kcalmol-I), $ = 55'. $ = -122'. (I) = -65" (minimum D, EcG, =1.90 kcalmol-I); r#J = 55",

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