The Photocyclodimers of 2,3‐Dihydro‐2,2‐dimethyl‐4H‐pyran‐4‐one |
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Authors: | Kerstin Schmidt,Jü rgen Kopf,Paul Margaretha |
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Abstract: | On irradiation (350 nm) in benzene solution, dihydropyranone 3 affords predominantly (75%) the cis‐anti‐cis HH‐dimer 4 , but in smaller amounts (12%) also dimer 5 , wherein one of the six‐membered rings is trans‐fused to the (central) cyclobutane ring. The constitution and configuration of 5 was fully elucidated by NMR‐analysis. On contact with SiO2, 5 isomerizes quantitatively to the cis‐anti‐cis HT‐dimer 7 , the structure of which was established by X‐ray crystal‐structure determination. |
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Keywords: | Enone photocyclodimerization Tricyclo[6.4.0.02,7]dodecanediones Pyrans Photocyclodimerization |
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