Viridin

Sorensen and coworkers used a domino conrotatory electrocydic ring-opening/ 6ji-disrotatory electrocyclization for the formation of ring C in the total synthesis of ( )-viridin (4-327) (Scheme 4.72) [112]. Heating 4-325 in the presence of a base followed by in-situ oxidation with DDQ afforded the tetracyde 4-326 in 83% yield. 

Alizarine cyanine green, alizarine viridine, brilliant alizarine viridine, etc. 

Viridin Inhibits seed germination and root growth... 

Mn3+, estimated to be about 198 kJ/g.ion in the andalusite Ml site, is that it increases the stability field of viridines in the pressure-temperature phase diagram for the system Al2Si05-(Al1 Mnx)2Si05 where x < 0.2 (Abs-Wurmbach et al., 1981 Langer, 1988). The influence of CFSE on the stability field of Mn3+ andalusite is discussed in chapter 7 ( 7.7.4.1). 

Cr3+ uvarovite (garnet), kammererite (chlorite), tawmawite (epidote) Mn3+ piemontite (epidote), thulite (zoisite), viridine (andalusite), blan-fordite (pyroxene), juddite and winchite (amphiboles)... 

Figure 7.7 Phase relationships in the system Al2Si05-Mn2Si05 in pressure-temperature-composition space projected onto the P,Tplane (from Abs-Wurmbach et al., 1983 Langer, 1988). Note the large increase of the andalusite stability field (And) with increasing Mn3+ contents plotted as mole per cent theoretical MnjSiO end-member. Insets (a) and (b) show how the triple point at 500 °C and 3.8 kb for pure Al2Si05 increases with rising Mn3 content of andalusite. [Legend to Mn-Al solid-solutions (ss) Ky = kyanite Sill = sillimanite Bm=braunite Cor=corundum Vir=viridine Qu=quartz.]...

Abs-Wurmbach, I. Longer, K. (1975) Synthetic Mn3+-kyanite and viridine, (Al2 xMn3+x)Si05, in the system Al203-Mn0-Mn02-Si02. Contrib. Mineral. Petrol., 49,21-38. 

Abs-Wurmbach, I., Langer, K. Tillmans, E. (1977) Structure and polarized absorption spectra of Mn3+-substituted andalusites (viridine). Naturwiss., 64, 527-8. 

Abs-Wurmbach, I., Langer, K., Schreyer, W. (1983) The influence of Mn3+ on the stability relations of the Al2Si05 polymorphs with special emphasis on manganoan andalusites (viridines)(Al, rMn3+ t)2(0ISi04) An experimental investigation. J. Petrol., 24,48-75. 

HYSCYLENE P PHENACETALDEHYDE DIMETHYL ACETAL a-TOLYL ALDEHYDE DIMETHYL ACETAL VIRIDINE... 

These natural substances range from simple monosubstituted benzo-furans, such as 5-methoxybenzofuran (44) (which has bactericidal propertiesand plays an important part in the biosynthesis of natural benzofurans ) to more complex benzofurans. They include polycyclic compounds with one naphthofuran or phenanthrofuran ring (tanshinones, etc.) and furanic diterpenes [methyl vinhaticoate (45), methyl voucapenate (46), viridine (47)i5o-i52 fungicidal metabolite)]. 

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