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Polar [4+2]‐ and [4+4]‐Photocycloadditions: Effects of Hybridization in Diradicals
Author(s) -
Kaupp Gerd,
Grüter HeinzWilli
Publication year - 1979
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.197908811
Subject(s) - anthracene , polar , substituent , adduct , chemistry , polar effect , photochemistry , medicinal chemistry , stereochemistry , organic chemistry , physics , astronomy
The control of photochemical reactions by polar substituents is of value for preparative applications. For example, anthracene (1a) reacts with butadiene to give the [4+2]‐ (2a) and the [4+4] adduct (3a) in the ratio of 20:1. The carbonitrile (1b) , on the other hand, leads to (2b), (3b) , and (4) (secondary product of a (3b) ‐isomer) in the ratio of 1:3.2:13.3. The polar substituent thus suppresses the [4 + 2] reaction ( a: X H; b: X CN).