Enantioselective catalytic conjugate addition of dialkylzinc reagents using copperphosphoramidite complexes; Ligand variation and non-linear effects Arnold, L.A.; Imbos, R.; Mandoli, A.; de Vries, A.H.M.; Naasz, R.; Feringa, B.L.

COMMUNICATIONSX-ray crystal structure analysis of [ (Li+)2(Zz-)(OEt,),(thf)2]: C44H76Li201r Pi, a = 9.782(1), b=14.594(1), c=15.640(1) A, a=74.999(2), p=81.977 (2), y = 83.417(2)", V=2128.34 A3, Z=2, pcalcd = 1.07 gem-), p =0.060 mm-I, T = 150 K, crystal dimensions ca. 0.25 x 0.50 x 0.50 mm3, 90 frames, 26428 measured (8101 unique) reflections, R = 0.0472 and R, = 0.0475 for 5823 reflections with t > 6o(l), maximum and minimum peak in final Fourier difference synthesis 0.58 and -0.42 e k 3 . Unit weights were used in the refinements. The asymmetric unit consists of half of a molecule of [(Li'),(ZZ-)(OEt2),] and half a molecule [(Li+)2(22-)(thf)4]. each located about an inversion center. X-ray crystal structure analysis of [ (K+)2(22-)( [18]crown-6),1: C26H88KZ0,2, P2.,ln, u = 13.959(1), b = 10.403(1), C = 19.733(1) A, b= 107.376(1)", V= 2740.31 A3, Z = 2, pca,d = 1.19 gcm-', # =0.22 mm-', T = 150 K, crystal dimensions ca. 0.20 x 0.25 x 0.40 mm', 90 frames, 29555 measured (6266 unique) reflections, R = 0.0422 and R,=0.0464 for 5403 reflections with t>3o(I), maximum and minimum peak in final Fourier difference synthesis 0.36 and -0.23 e k 3 . A weighting scheme based on an optimized three-coefficient Chebyshev polynomial was used in the refinements [31]. General crystallographic information: Data were collected on an Enraf-Nonius DIP 2000 image plate diffractometer using graphite-monochromated Mo,, radiation (step of 2" between frames, B, , = 26"). Corrections were made for Lorentz and polarization effects [32]. The structures were solved by direct methods using SIR92[33] and refined by using full-matrix least-squares. Hydrogen atoms were fixed in geometrically idealized positions and allowed to ride on their attached carbon atoms. Corrections for the effects of anomalous dispersion and isotropic extinction (through an overall extinction coefficient) [34] but not for absorption, were made in the final stages of refinement. All crystallographic calculations were performed by using the Oxford CRYSTALS system[35] running on a Silicon Graphics Indigo R4000 computer. Crystallographic data (excluding structure factors) for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-100693. Copies of the data can he obtained free of charge on application to The Director, CCDC, 12 Union Road, Cambridge CB21 lEZ, UK

An efficient enantioselective intramolecular Heck reaction of cyclohexadienones, using readily available and modular TADDOL-based mono- and bidentate phosphoramidites as chiral ligands and not requiring any additives, has been developed. Excellent enantioselectivities up to 96% ee are reached for the first time in a Heck reaction with monodentate ligands.

Monodentate phosphoramidites have been used for the first time as chiral ligands in the Rh-catalyzed enantioselective conjugate addition of arylboronic acids to enones, unsaturated esters, lactones, and nitro alkenes. High reaction rates and ee's up to 89% have been obtained.

ZUSCHRIFTENKristallstrukturdaten von [ ( K+)2(22-)( [18]krone-6),]: C&,H,K,OI2, P2,/n, a = 13.959(1), 6=10.403(1), ~=19.733(1)A,fi=107.376(1)', V=2740.31 A', 2 = 2 , phcr= 1.19 gcm-', p =0.22 mm-l, T = 150 K; Kristalldimension ca. 0.20 x 0.25 x 0.40 mm, 90 Rahmen, 29 555 gemessene (6266 unabhangige) Reflexe, R = 0.0422 und R, =0.0464 fur 5403 Reflexe mit I > 3 4 I ) ; m a x h i n . Restelektronendichte in der letzten Differenz-Fourier-Synthese: 0.361 -0.23 e A-3. Fur die Strukturverfeinerung wurde ein Gewichtungsschema, das auf einem optimierten Drei-Koeffizienten-Chebyshev-Polynom beruht, verwendet [ 311. Allgemeine Informationen zu den Kristallstrukturanalysen: Die Daten wurden auf einem Enraf-Nonius-DIP-2000-Diffraktometer mit Flachendetektor unter Venvendung graphitmonochromatisierter Mo,,-Strahlung (2"-Schritte zwischen den Rahmen, 6,,, = 26") gemessen; Korrekturen fur Lorentz-und Polarisationseffekte [32]. Die Strukturen wurden mit Direkten Methoden unter Verwendung des Programmpaketes SIR92[33] gelost und nach dem Verfahren der kleinsten Fehlerquadrate mit voller Matrix verfeinert. Wasserstoffatome wurden geometrisch ideal positioniert und mit einem Reitermodell verfeinert; Korrekturen fur die Effekte anomaler Dispersion und isotroper Extinktion (mittels eines Gesamtextinktionskoeffizienten [34]) in den letzten Cyclen der Verfeinerung; keine Korrektur fur Absorptionseffekte. Alle kristallographischen Berechnungen wurden mit den in CRYSTALS[35] enthaltenen Routinen auf einem Indigo-R4000-Computer von Silicon Graphics durchgefuhrt. Die kristallographischen Daten (ohne Strukturfaktoren) der in dieser Veroffentlichung beschriebenen Strukturen wurden als supplementary publication no. CCDC-100693 beim Cambridge Crystallographic Data Centre hinterlegt. Kopien der Daten konnen kostenlos bei folgender Adresse in GroBbritannien angefordert werden: The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ (Telefax: Int. + 1223/ 336-033 ;

Enantioselective copper phosphoramidite-catalyzed conjugate addition of dialkylzinc reagents (R 2 Zn) to several 4,4-disubstituted cyclohexadienones was achieved with dr's up to 99/1 and ee's up to 99%.Organocopper compounds are among the most widely used reagents for C-C bond formation by virtue of their versatility in conjugate addition reactions. 1 Considerable progress has been made in the enantioselective copper-catalyzed 1,4-addition to prochiral enones, and this method offers an attractive way to form enantiomerically enriched -substituted carbonyl compounds. 2 Recently, we reported a novel chiral Cu(OTf) 2 -phosphoramidite catalyst based on ligand L*-1 (for L*-1 see Figure 1) which allowed for the first time highly enantioselective catalytic conjugate addition of several (functionalized) dialkylzinc reagents to cyclic R, -unsaturated ketones. 3,4 Enantioselective annulations via a 1,4-addition-aldol cyclization protocol, employing functionalized organozinc reagents, were also achieved with this catalyst. 5 Cyclohexadienones are attractive substrates for conjugate additions as the chiral products may be subject to further (1) For an excellent review on recent progress in organocopper chemistry, see: Krause, N., Gerold, A. Pineschi, M.; Arnold, L. A.; Imbos, R.; De Vries, A. H. M. Angew. Chem., Int. Ed. Engl. 1997, 36, 2620 (4) Highly enantioselective rhodium-catalyzed asymmetric 1,4-addition of aryl-and alkenylboronic acids to enones has been reported by Hayashi et al.: Takaya, Y.; Ogasawara, M.; Hayashi, T.

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