The [3+4] cycloaddition between furan and the oxyallyl cation generated from 1-bromo-1-phenylpropan-2-one (4), resulted in the formation of 2-phenyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (5) in 30% yield. This compound was further converted into 2-phenyl-6,7-exo-isopropylidenedioxi-8-oxabicyclo[3.2.1]oct-2-ene (13) in 35.4% yield. The selective effect of compound (13) and its isomer 3-phenyl-6,7-exo-isopropylidenedioxi-8-oxabicyclo[3.2.1]oct -2-ene (1a) on the radicle growth of Sorghum bicolor L. (sorghum) and Cucumis sativus L. (cucumber) were evaluated. For both plants, compound 13 showed to be more potent than its isomer 1a.

Ácido orselínico é benzilado e 4-benziloxi-2-hidroxi-6-metilbenzoato de benzila (7) é então convertido no composto desejado (2), o qual é o constituinte aromático de calicheamicin gama1I.

Orsellinic acid (6) was benzylated, and the benzyl 4-benzyloxy-2-hydroxy-6-methylbenzoate (7) was then elaborated into the title compound (2), which is the aromatic constituent of calicheamicin gamma1I.

A síntese de vários análogos do 8-oxabiciclo[3.2.1]oct-6-en-3-ona é relatada. O efeito desses compostos e do ácido 4-oxoexanóico sobre a germinação e crescimento radicular do Sorghum bicolor foi avaliado. Na concentração de 100 ppm os compostos 3-(metoxicarbonilmetil)-8-oxabiciclo[5.3.0]dec-4-eno-2,9-diona (13) e ácido 4-oxoexanóico (17) apresentaram efeito estimulador do crescimento radicular de 33-35% e a 1000 ppm um efeito inibitório foi observado em ambos os casos (29% (13) e 80,2% (17). Todos os outros compostos inibiram o crescimento radicular a 100 e 1000 ppm. Nenhum efeito significativo foi observado sobre a taxa de germinação

The synthesis of several analogues of 8-oxabicyclo[3.2.1]oct-6-en-3-one is reported. The effect of these compounds and 4-oxohexanoic acid on the germination and radicle growth of Sorghum bicolor was evaluated. At 100 ppm compounds 3-(methoxycarbonylmethyl)-8-oxabicyclo[5.3.0]dec-4-ene-2,9-dione (13) and 4-oxohexanoic acid (17) showed 33-35% stimulatory radicle growth, and at 1000 ppm a 29% (13) and 80.2% (17) inhibition was observed. All the other compounds showed an inhibitory effect on the radicle growth at 100 and 1000 ppm. None of the compound had a clear effect on the germination rate.