Collect. Czech. Chem. Commun. 1996, 61, 930-940

Pregnane-Type Brassinosteroids with a Four-Carbon Ester Functionality in Position 20

Ladislav Kohouta, Alexander Kasala and Miroslav Strnadb

a Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic
b Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 772 00 Olomouc, Czech Republic


Analogues of brassinolide and castasterone, containing an ester functionality with four carbon atoms in the position 20 of the pregnane skeleton, have been prepared. In the bean second internode assay the most effective compounds were (20R)-2α,3α,20-trihydroxy-5α-pregnan-6-one 20-isobutyrate (6d) and (20R)-2α,3α,20-trihydroxy-B-homo-7-oxa-5α-pregnan-6-one 20-isobutyrate (7d). On the other hand, (20R)-2α,3α,20-trihydroxy-B-homo-6-oxa-5α-pregnan-7-one 20-heptafluorobutyrate (8) was the first compound with the retarding effect in the same test.

Keywords: Brassinosteroids; PGH; Synthesis; Antibrassinolide activity.