Cyclic guanidine alkaloid synthesis

Recent Developments in the Synthesis of Cyclic Guanidine Alkaloids... 

This volume opens with two specialized reviews, not restricted to work published in 2013 Recent Developments in the Synthesis of Cyclic Guanidine Alkaloids written by Matthew G. Donahue, and Heterocyclic chemistry a complete toolbox for nanostructured carbon materials written by Luisa Lascialfari, Stefano Fedeli, and Stefano Cicchi. The remaining chapters examine the 2013 literature on the common heterocycles in order of increasing ring size and the heteroatoms present. The Index is not fully comprehensive, however the Contents pages list all the subheadings of the chapters which will assist in accessibility for readers. 

In the examples shown in Schemes 2.19 and 2.20, neither the substrates nor the products were sensitive to elevated temperatures or acid and so dehydration was accomplished by azeotropic distillation. However, acetalisation of acid-sensitive substrates can be a major challenge. For example, a synthesis of the Crambescidin family of guanidine alkaloids was impeded by problems with the acid sensitivity of the ketone 2L1 [Scheme 2.21]. The triethylsilyl group made the desired acetalisation sluggish the firee alcohol reacted faster but it also underwent very easy -elimination. Conditions that accomplished removal of the triethylsilyl group and acetalisation without competing dehydration entailed reaction of 21.1 with the cyclic ortho ester 213 and 1,3-propanediol in the presence of Amberlyst-15 at room temperature in acetonitrile. The required hydro-... 

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