Natural SOMO-catalysis

Soon afterward, MacMillan and co-workers [142, 143] also reported enantio-selective intramolecular a-arylation of aldehydes via organo-SOMO catalysis. [Fe(Phen)3l [PFsl 3, instead of CAN, as a single-electron oxidant together with designed imidazolidinone catalysts LXVIII and LXIX were found to be optimal for reaction efficiency and enantioselectivity (Scheme 8.35). Moreover, ortho selectivity, when 1,3-disubstituted aromatic systems were used, was observed. Methodologies presented by Nicolaou and MacMillan represent a useful tool for the total synthesis of various naturally occurring compounds, such as dimethyl calamenene, tashiromine, and so on. 

SOMO catalysis is one of the most recent developments in asymmetric organocatalysis and its considerable promise has been shown thus far in a limited number of complex natural product syntheses. As this unprecedented (/mpo/wng-methodology enables stereoselective transformations that are otherwise barely possible, further applications in demanding syntheses can be expected soon by others (Table 4). 

Um JM, Gutierrez O, Schoenebeck F, Houk KN, MacMillan DWC (2010) Nature of Intermediates in Organo-SOMO Catalysis of a-Arylation of Aldehydes. J Am Chem Soc 132 6001... 

Enantioselective intramolecular F-C-type a-arylation of simple aldehydes, based on the concept of organo-SOMO catalysis, paved the way to the synthesis of two natural products via very sophisticated and well-designed strategies (Section 35.2.1). In 2009, Nicolaou and coworkers published the synthesis of the antitumor natural product demethyl calamenene [50] and, independently, in the same year the group of MacMillan developed an elegant route to (—)-tashiromine (Scheme 35.29) [5b]. 

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