%0 Journal Article
%A Chou, Ta-shue
%A Chen, Hong-Chuan
%A Yang, Woei-Chang
%A Li, Wan-Sheung
%A Chao, Ito
%A Lee, Shwu-Jiuan
%D 2000
%T Type-Two Intramolecular Diels−Alder Reactions of
Pyrazolo-o-quinodimethanes
%U https://acs.figshare.com/articles/journal_contribution/Type-Two_Intramolecular_Diels_Alder_Reactions_of_Pyrazolo-_i_o_i_-quinodimethanes/3720495
%R 10.1021/jo9917285.s002
%2 https://ndownloader.figshare.com/files/5812191
%K Thermolysi
%K tricyclic
%K substitution position
%K pyrazolo
%K intramolecular
%K regioselectivity
%K isomeric series
%K demostrated
%K Diel
%K Pyrazolo
%K material
%K quinodimethane
%K sulfolene
%K pyrazole
%K acryloyloxy
%K extrusion
%K Intramolecular
%K thieno
%K dihydro
%X Two isomeric series of homologous N-(acryloyloxy)alkylated pyrazolo-3-sulfolenes 10a−c and 18a−c
have been efficiently synthesized from a common starting material, 4,6-dihydro-1H-thieno[3,4-c]pyrazole (5). Thermolysis of these fused 3-sulfolenes provides the corresponding o-quinodimethanes
which simultaneously undergo “type-two” intramolecular Diels−Alder reactions to form two- and
three-atom-bridged tricyclic pyrazoles which are otherwise difficult to prepare. It was also
demostrated that, depending on the N-substitution position of the pyrazolo-fused 3-sulfolenes, the
temperature required for the thermal extrusion of SO2 and the regioselectivity of the T2-IMDA
reactions were influenced substantially.
%I ACS Publications