New derivatives of 2α,4α‐dimethyl‐8‐oxabicyclo[3.2.1]oct‐6‐en‐3‐one

ABSTRACT Several new compounds with potential herbicidal activity were synthesized from 2α,4α‐dimethyl‐6,7‐exo‐isopropylidenedioxy‐8‐oxabicyclo[3.2.1]octan‐3‐one (4). Seven aromatic alcohols were prepared by reaction of (4) with aryllithium reagents, where the aryl groups were 4‐ethoxyphenyl (5, 70% yield), 4‐ethylphenyl (6, 82% yield), 4‐butylphenyl (7, 78% yield), 4‐tert‐butylphenyl (8, 81% yield), 2,4‐dimethoxyphenyl (9, 75% yield), 2‐ethylphenyl (10, 12% yield) and para‐(4‐bromophenoxy)phenyl (11, 24% yield). Reaction of the acetonide (4) with Grignard reagents formed also four aliphatic alcohols where the alkyl groups are ethyl (13, 78%), butyl (14, 85%), hexyl (15, 81%) and octyl (25, 92%). The alcohols (5), (6), (7), (8), (13), (14), (15) and (25) were reacted with thionyl chloride in pyridine, forming their respective alkenes (17, 76%), (18, 74%), (19, 83%), (20, 73%), (22, 78%), (26, 62%), (23, 77%) and (24, 66%). The effect of these compounds, at the concentration of 5.5 µg g−1, on the development of radicle and aerial parts of Sorghum bicolor (L) Moench, Euphorbia heterophylla L, Brachiaria decumbens and Desmodium tortuosum DC was evaluated. Copyright © 2003 Society of Chemical Industry