Photoswitching of stereoselectivity in catalysis using a copper dithienylethene complex

Angewandte Chemie - International Edition

Volumn 44, Issue 13, 2005, Pages 2019-2021

  Sud, David ^a   Norsten, Tyler B ^b   Branda, Neil R ^a  

^a SIMON FRASER UNIVERSITY   (Canada)

^b NATIONAL RESEARCH COUNCIL CANADA   (Canada)

Author keywords

Copper; Enantioselectivity; Homogeneous catalysis; Molecular switches; Photochromism

Indexed keywords

CATALYST SELECTIVITY; CHELATION; COMPLEXATION; COPPER COMPOUNDS; IRRADIATION; REACTION KINETICS; STYRENE; ULTRAVIOLET RADIATION;

CHIRALITY; CYCLOPROPANATION; PHOTOSWITCHING; STEREOSELECTIVITY;

STEREOCHEMISTRY;

EID: 16844368309     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200462538     Document Type: Article

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16. -2) were used to carry out the ring-closing reaction of 3o to 3c with and without copper(I). The ring-opening reactions were carried out using the light of a 150-W tungsten source that was passed through a 434 nm cutoff filter to eliminate higher energy light.
17. -1, 95:5 hexanes:2-propanol). Detection was adjusted at 220 nm, which is a maximum in the absorption spectrum of the trans isomers. A solution of trans enantiomers gave two peaks separated in their retention time by 3.7 min. The cis isomers were only separated by 0.4 min and were not baseline separated. It was however possible to distinguish both maxima and by deconvoluting the data using the software provided with the HPLC, the separate peak areas were obtained. The amount of catalyst can be lowered to 1 mol % with respect to the ethyl diazoacetate to produce 120 mg (63 %) of the cyclopropanated products as a mixture of stereoisomers after workup and isolation by centrifugal chromatography (2 % ethyl acetate/hexanes).