Synthesis and Unambiguous Stereochemical Determination of 1-exo- and 1-endo-1-Aryl-1,2,2a,8b-tetrahydro-3H-benzo[b]cyclobuta[d]pyran-3-ones

Autor:	Ikuo Kawasaki, Yuka Nishino, Junko Fukao, Yadav Navnath Dnyanoba, Shunsaku Ohta, Kumiko Miura, Masayuki Yamashita, Masaki Nagahama, Tomoki Inaba, Sachiko Kosaka
Rok vydání:	2006
Předmět:	Pharmacology chemistry.chemical_compound Stereochemistry Chemistry Pyran Aryl Organic Chemistry Stereoselectivity General Medicine Ring (chemistry) Coumarin Cycloaddition Analytical Chemistry
Zdroj:	ChemInform. 37
ISSN:	1522-2667 0931-7597
DOI:	10.1002/chin.200606144
Popis:	Stereoselective preparation of 1-exo-substituted 1,2,2a,8b-tetrahydro-3H-benzo[b]cyclobuta[d]pyran-3-ones (2) was achieved by photo [2+2] cycloaddition of olefins to 3-substituted coumarins (1). 1-endo-Substituted 1,2,2a,8b-tetrahydro-3H-benzo[b]cyclobuta[d‖pyran-3-ones (3) were stereoselectively prepared by hydrogenation over the Pd-carbon of 2a,8b-dihydro-3H-benzo[b]cyclobuta[d]pyran-3-ones (5), which were obtained by photo [2+2] cycloaddition of the coumarins (1) to acetylenes. The stereochemistry of 1-exo- and 1-endo-arylcyclobutanes (2 and 3) could be easily determined on the basis of the 1 H-NMR spectrum, in which the C8-proton in 3 was strongly shielded by the 1-aryl ring but that in 2 was not.
Databáze:	OpenAIRE
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