Aggarwal total synthesis

Aggarwal and Olofsson have developed a direct asymmetric a-arylation of prochiral ketones using chiral lithium amide bases and diaryliodonium salts [881]. In a representative example, the deprotonation of cyclohexanone derivative 684 using chiral Simpkins (/ ,/ )-base followed by reaction with the pyridyl iodonium salt gave the arylated product 685 in 94% ee (Scheme 3.275). This reaction has been employed in a short total synthesis of the alkaloid (-)-epibatidine [881]. 

Aggarwal performed the stereoselective total synthesis of solandelactones E and F by a stereocontrolled allylboration reaction of the eight-membered lactone 83, which was prepared by cyclization of 81 (Scheme 5.28) [76]. Treatment of the seco-acid 81 under Yamaguchi conditions according to the protocol previously established by Martin et al. [73] and Pietruszka [75] for a similar reaction resulted in the formation of the target lactone 82 in good yield. 

In 2002, Aggarwal et al. developed an efficient route to unsaturated carboxylic acid 44 by a palladium-catalyzed Heck cyclization/carbonylation cascade of vinylic bromide 43 [18a] (Scheme 6.9). By choosing the appropriate phosphine ligand and intensive optimization, the formation of linear carboxylic acid 45 and the direct Heck-type product can be restricted. Recently, the same group applied this cascade transformation as the key step to the total synthesis of avenaciolide [18bJ. 

Robinson, A. and Aggarwal, V.K. (2010) Asymmetric total synthesis of solandelactone E Stereocontrolled synthesis of the 2-ene-l,4-diol core through a lithiation-borylation-allylation sequence. Angeiv. Chem. Int. Ed., 49, 6673-6675. 

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