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Title: Oxygen-initiated stereoselective thermal isomerisation of a cyclobutane derivative in the solid state
Authors: Chanthapally, Anjana
Yang, Hui
Quah, Hong Sheng
Webster, Richard D.
Schreyer, Martin K.
Wong, Ming Wah
Vittal, Jagadese J.
Keywords: DRNTU::Science::Chemistry::Organic chemistry::Oxidation
Issue Date: 2014
Source: Chanthapally, A., Yang, H., Quah, H. S., Webster, R. D., Schreyer, M. K., Wong, M. W., et al. (2014). Oxygen-initiated stereoselective thermal isomerisation of a cyclobutane derivative in the solid state. Chemistry - a European journal, 20(48), 15702-15708.
Series/Report no.: Chemistry - a European journal
Abstract: Solid-state [2+2] photochemical cycloaddition reactions have been extensively studied after the classical work of Schmidt in the 1960s. Of these, trans-1,2-bis(4′-pyridyl)ethylene (bpe) is one of the well-studied alkenes to synthesize tetrakis(4-pyridyl)cyclobutane (tpcb). However, almost all the solid-state [2+2] cycloaddition reactions of bpe yielded, almost exclusively, one of the four possible isomers, namely, the rctt-tpcb (r=regio c=cis and t=trans). Here we describe a stereoselective synthesis of the tetrahedrally disposed rtct-tpcb by the solid-state thermal isomerization of the rctt-isomer in atmospheric air. We propose that this isomerization occurs through a topochemical unimolecular mechanism by a radical chain pathway, initiated by molecular oxygen. This is supported by the nature of products formed in air and nitrogen, detection of a radical in ESR spectral studies, ESI-MS crossover experiments, VT PXRD studies along with QM, MD and docking calculations. The formation of a unique isomer by thermal isomerization may be a general phenomenon to quantitatively synthesize other useful stereoisomers from the existing isomers of cyclobutane derivatives.
ISSN: 0947-6539
DOI: 10.1002/chem.201405228
Rights: © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Fulltext Permission: none
Fulltext Availability: No Fulltext
Appears in Collections:SPMS Journal Articles

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