2.2- Dimethyl-6,7-dimethoxy-chromene

H-Chromene, 6,7-dimethoxy-2,2-dimethyl-application, 3, 881 2H-Chromene, 2,2-dimethyl-addition reactions, 3, 670 fluorinated... 

Isolation and identification of the two natural antijuvenile hormones revealed two simple chromenes 7-methoxy-2,2-dimethyl chromene and 6,7-dimethoxy-2,2-dimethyl chromene (Figure 3). Since these compounds induced precocious metamorphosis, we called them Precocene I and II respectively. Subsequently we found that both compounds had been previously identified and synthesized ( 15, 16, 17). We developed an efficient synthesis for these compounds shown in Figure 4. 

Entsprechend entsteht aus 4-Oxo-4H-chromen und Cyclopenten 8-Oxo-(benzo-3-oxa-tricyclo[6.3.0.02 ]undecen-(4)y 3. MitButin- (2) wird 7-Oxo-9,10-dimethyl-(3,4-benzo-2-oxa-bicyclo[4.2.0]ocladien-(3,7)y gcbildet1.2. und mit 1,1-Dimetkoxy-athylen ergibt sich 10,10-Dimethoxy-7-oxo-(benzo-2-oxa-bicyclo [4.2.0] ocfen-(J)) und 3,3-Dimethoxy-oxetan-(2-spiro-7y- 10,10-dime,lhoxy-(ljfMzo-2-oxa-bicyclo[4.2.0 octen-(3)y2>3. 

The bioactivities of precocene I, 7-methoxy-2,2-dimethyl chromene, and precocene II, 6,7-dimethoxy-2,2-dimethyl chromene, are well established (Fig. (7)). These two compounds have been isolated from plants throughout the family Asteraceae [129-136, 154]. The chemical data for these compounds and references for their synthesis are compiled in Appendix IV, Tables 13 and 14. There is a wealth of information on the effects of these compounds on various insect species [42, 137]. For simplicity, we will focus on the effects of precocene II on the susceptible Hemipteran bug, Oncopeltus fasciatus. 

Chromene ring formation can be effected by oxidative cyclisation of 2-prenylphenols or by reaction of pyrano compounds with DDQ (dichlorodicyanobenzoquinone), by reduction of a chromone with a hydride followed by dehydration with a toluenesulphonic acid, and directly by the use of 1,1-dimethoxy-3,3-dimethyl-3-hydroxypropane. 

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