Loganin, synthesis

The diazomethane methodology has previously been applied by several other groups to expand cyclobutanones. For example, in Fleming s loganin synthesis, 53,54) when the cyclobutanone (151) was allowed to react with diazoethane, (152) was isolated as a mixture of stereoisomers. Removal of the chlorine atom and equilibration of the methyl group with NaOMe converted (152) to the ketone (153) 53,54). 

A remarkable combination of a photochemical [2+2] cycloaddition with a retro-aldol reaction and cyclization is the so-called de Mayo reaction. Biichi and coworkers have used this method for the total synthesis of loganin (5-35). Thus, reac-... 

The key step in Biichi s total synthesis of loganin (5i)23 made use of the expansion of a four-membered ring to an oxygen-containing heterocycle by retro-aldol reaction. This strategy was later exploited by Tietze in his total synthesis of hydroxyloganin (54) as well as hydroxyloganic acid (55) 24). 

The total synthesis of optically active loganin (53) was accomplished by Partridge 25), who photolyzed a solution of the chiral acetate (60) and the ester (56). The intermediate (61) rearranged to the chiral hemiacetal (62), which served as a key compound in the synthesis of chiral loganin (53)15). 

Au-Yeung and Fleming have devised a new alternative synthesis of loganin (590) based upon allylsilane chemistry.438 The bicyclic ketone 586, obtained by cycloaddition of dichloroketene to trimethylsilylcyclopentadiene, was monodechlorina-ted, ring expanded with diazoethane, and again dehalogenated prior to equilibration... 

Sultam-modified acrylates undergo [4 + 2]-cy-cloadditions with 1,3-dienes with excellent endo- and side-selectivity in the presence of EtAlCl2 or TiCl4 [7-9]. This feature could be used for an effective synthesis of the loganin-aglycon 9 (Scheme 2) [10] ... 

Activattd dimethyl sulfoxide oxidations have been fairly well used in the synthesis of monoterpenes, as seen in the oxidation to an aldehyde of the alcohols (40), en route to loganin aglycone, and (41), a precursor in a synthesis of specionin (equation 16). ... 

Another useful application of (+)-IPC2BH is the synthesis of loganin, an important building block in much of the plant world (Scheme 8) Treatment of the diene (38)... 

Asymmelric kydroboradon. A key step in an asymmetric synthesis of loganin (I), a key intermediate in the biosynthesis of indole and monoterpene alkaloids, involved... 

Tai, H.-M., Chang, M.-Y., Lee, A.-Y., Chang, N.-C. A Versatiie Diquinane from Fuivene as a Buiiding Biock in Naturai Product Synthesis. 1. A Faciie Synthesis of the iridoids Loganin and Sarracenin. J. Org. Chem. 1999, 64, 659-662. 

A loganin aglucon synthesis has been developed as shown in Eq. 127 245>. Here the key step is the regioselective [3+2]-cycloaddition of 2-cyclopentenone and 3-[(tri-methylsilyl)methyl]-3-buten-2-ylmethylcarbonate. 

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