Rearrangements of the Diels−Alder Cycloadducts Obtained from
Acetylenic Sulfones and 1,3-Diphenylisobenzofuran
Thomas G. Back
Masood Parvez
Huimin Zhai
10.1021/jo060598e.s006
https://acs.figshare.com/articles/dataset/Rearrangements_of_the_Diels_Alder_Cycloadducts_Obtained_from_Acetylenic_Sulfones_and_1_3_Diphenylisobenzofuran/3072022
1,3-Diphenylisobenzofuran afforded Diels−Alder cycloadducts <b>4a</b>,<b>b</b> with <i>n</i>-butyl- and phenyl-substituted
acetylenic sulfones <b>3a</b>,<b>b</b>, respectively. The products underwent various types of rearrangements under
pyrolytic, acid-catalyzed, and photochemical conditions. In the presence of acid, or upon heating in xylenes,
they afforded the ketones <b>5a</b>,<b>b</b>. In addition, the dehydration product <b>7a</b> was produced from the pyrolysis
of <b>4a</b>, and the unexpected transposed ketone <b>6b</b> was generated under acid-catalyzed or pyrolytic conditions
from <b>4b</b> via a postulated epoxide intermediate. The photolysis of <b>4a </b>afforded ketone <b>5a</b> as the sole
isolated product, whereas <b>5b</b> afforded oxepin <b>8b</b> and indenyl phenyl ketone <b>9b</b>. The formation of the
latter two products can be rationalized by a series of pericyclic reactions. These include an intramolecular
[2+2] cycloaddition, followed by a 1,3-dipolar cycloreversion, for the transformation of <b>4b</b> to <b>8b</b> and a
series of electrocyclic and [1,3]sigmatropic reactions to convert <b>8b</b> into <b>9b</b>.
2006-07-07 00:00:00
series
dehydration product 7
Diel
4 b
8 b
ketone 6 b
pyrolytic
oxepin 8 b
indenyl phenyl ketone 9 b