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Single step formation of novel tricyclic systems on [3 + 2] photocycloaddition of 3-(1-alkynyl)cyclohexenones to methoxyalkenes

✍ Scribed by Paul Margaretha; H.-J Rathjen; William C Agosta

Publisher
Elsevier Science
Year
1990
Tongue
French
Weight
208 KB
Volume
31
Category
Article
ISSN
0040-4039

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✦ Synopsis

Abstracti Irradiation of lb (X -350 nm) in ten-butyl alcohol solution containing 5 leads to the novel ring system 9b in a single step. Similar reactions occur between la and both 5 and 6. Mechanisms of these transformations are discussed.

b-radiation of alkynylcyclohexenone la in the presence of tetramethylethylene leads to formation of [3 +2] cycloaddition products such as 2,* and we have explained this and related reactions3 by way of an initially formed 1,4 alkyl propargyl biradical3 that closes 1,s on the triple bond to yield carbene 4.

Hydrogen transfer in 4 then furnishes 2. We now report a significant modification of this process that permits construction of unusual tricyclic systems in a single step through use of alkoxyalkenes such as 5 and 6 as addends. Irradiation (A -350 run) of ,1b4 in cc+butyl alcohol solution containing -10 equiv. of

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