Pentalene,1,3a,4,6a-tetrahydro-3,6-diphenyl-, (3aR,6aR)-

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CAS: 947503-81-3
MF: C20H18
MW: 258.35692
Synonyms: Pentalene,1,3a,4,6a-tetrahydro-3,6-diphenyl-, (3aR,6aR)-

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Sabine Laschat

Institut für Organische Chemie der Universit?t Stuttgart
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Co-reporter: Sarah Helbig, Kirill V. Axenov, Stefan Tussetschläger, Wolfgang Frey, Sabine Laschat
pp: 3506-3509
Publication Date(Web):4 July 2012
DOI: 10.1016/j.tetlet.2012.04.130
Chiral tetrahydropentalenes (3aR,6aR)-1 have been prepared and used as ligands in the Rh-catalyzed 1,4-addition of 1-alkenylboronic acids to cyclic enones 5. It has been discovered that the stereochemistry of the reaction was controlled by the steric properties of the aryl groups in 1 rather than their electronic nature. In the vinylation with (E)-2-phenylethenylboronic acid 5, ligands (3aR,6aR)-1 provided enantioselectivity up to 87% ee and gave high yields of ethenylketones 6 in the presence of 1 (6.6 mol %). The configuration of all ketone products obtained with (3aR,6aR)-1 is (S). Rh-catalyzed reaction of cyclopentenone 4a and (Z)-propenylboronic acid 7 in the presence of ligands (3aR,6aR)-1 yielded at 50 °C an inseparable mixture of (Z)- and (E)-ketones 8 with (Z)-8 as the major product and both in only moderate enantiomeric excess.Chiral tetrahydropentalenes catalyze the 1,4-addition of vinylboronic acids to cyclic enones in the presence of the Rh-complexes. The stereochemistry of the reaction was controlled by the steric properties of the aryl groups in the tetrahydropentalenes as well as by the substitution pattern of the boronic acids.Image for unlabelled figure

Ming-hua Xu

Shanghai Institute of Materia Medica
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