Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol

While bromination of γ-tocopherol (2) with elemental bromine affords 5-bromo-γ-tocopherol quantitatively (3), the analogous reaction of its truncated model compound, 2,2,7,8-tetramethylchromanol (2a) is known to be accompanied by side reactions and to produce hitherto unknown byproducts. These compo...

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Main Authors:	Böhmdorfer, Stefan, Kloser, Elisabeth, Patel, Anjan, Gille, Lars, Mereiter, Kurt, Rosenau, Thomas
Format:	Online
Language:	English
Published:	Pergamon Press 2011
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3190837/

id	pubmed-3190837
recordtype	oai_dc
spelling	pubmed-31908372011-10-24 Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol Böhmdorfer, Stefan Kloser, Elisabeth Patel, Anjan Gille, Lars Mereiter, Kurt Rosenau, Thomas Article While bromination of γ-tocopherol (2) with elemental bromine affords 5-bromo-γ-tocopherol quantitatively (3), the analogous reaction of its truncated model compound, 2,2,7,8-tetramethylchromanol (2a) is known to be accompanied by side reactions and to produce hitherto unknown byproducts. These compounds originate from pyrano[3,2-f]chromene (6), a byproduct in the synthesis of model compound 2a, which affords bromochromene 7 as the major product. The reaction mechanism was shown to proceed via chromene 8 and its 1,2-dibromo addition compound 9, which eliminates HBr in an E1 process to finally afford 7. Analytical data including crystal structures of both 6 and 7 are reported. Pergamon Press 2011-08-26 /pmc/articles/PMC3190837/ /pubmed/22031788 http://dx.doi.org/10.1016/j.tet.2011.06.070 Text en © 2011 Elsevier Ltd. This document may be redistributed and reused, subject to certain conditions (http://www.elsevier.com/wps/find/authorsview.authors/supplementalterms1.0) .
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Böhmdorfer, Stefan Kloser, Elisabeth Patel, Anjan Gille, Lars Mereiter, Kurt Rosenau, Thomas
spellingShingle	Böhmdorfer, Stefan Kloser, Elisabeth Patel, Anjan Gille, Lars Mereiter, Kurt Rosenau, Thomas Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol
author_facet	Böhmdorfer, Stefan Kloser, Elisabeth Patel, Anjan Gille, Lars Mereiter, Kurt Rosenau, Thomas
author_sort	Böhmdorfer, Stefan
title	Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol
title_short	Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol
title_full	Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol
title_fullStr	Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol
title_full_unstemmed	Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol
title_sort	novel tocopherol derivatives. part 32: on the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol
description	While bromination of γ-tocopherol (2) with elemental bromine affords 5-bromo-γ-tocopherol quantitatively (3), the analogous reaction of its truncated model compound, 2,2,7,8-tetramethylchromanol (2a) is known to be accompanied by side reactions and to produce hitherto unknown byproducts. These compounds originate from pyrano[3,2-f]chromene (6), a byproduct in the synthesis of model compound 2a, which affords bromochromene 7 as the major product. The reaction mechanism was shown to proceed via chromene 8 and its 1,2-dibromo addition compound 9, which eliminates HBr in an E1 process to finally afford 7. Analytical data including crystal structures of both 6 and 7 are reported.
publisher	Pergamon Press
publishDate	2011
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3190837/
_version_	1611480043570069504

Novel tocopherol derivatives. Part 32: On the bromination of pyrano[3,2-f]chromenes related to γ-tocopherol

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