Premium
The Photocyclodimers of 2,3‐Dihydro‐2,2‐dimethyl‐4 H ‐pyran‐4‐one
Author(s) -
Schmidt Kerstin,
Kopf Jürgen,
Margaretha Paul
Publication year - 2006
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200690183
Subject(s) - chemistry , dimer , pyran , cyclobutane , benzene , ring (chemistry) , crystal structure , stereochemistry , crystallography , organic chemistry
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 SiO 2 , 5 isomerizes quantitatively to the cis‐anti‐cis HT ‐dimer 7 , the structure of which was established by X‐ray crystal‐structure determination.