1020850-91-2Relevant academic research and scientific papers
Synthesis of (Z)-Trisubstituted olefins by decarboxylative Grob-Type fragmentations: Epothilone D, discodermolide, and peloruside A
Prantz, Kathrin,Mulzer, Johann
supporting information; experimental part, p. 485 - 506 (2010/06/14)
Methyl-branched (Z)-trisubstituted olefins are found in many polyketides with interesting biological activity, such as epothilone D (1), discodermolide (3), and peloruside A (2). Despite the employment of numerous different strategies, this motif has often been the weak point in total synthesis. Thus, we present a novel hydroxideinduced Grob-type fragmentation as an easy access to trisubstituted olefins. In our case, β-mesyloxy δ-lactones with three stereogenic centers were chosen whose fragmentation underlies a high stereoelectronic control. Major challenges in the syntheses were the instailation of quaternary stereocenters, achieved by enzymatic desymmetrization of meso-diesters and by aluminiumpromoted stereoselective rearrangement of chiral epoxides, respectively. Different aldol strategies were developed for the formation of the fragmentation precursors. Additionally a short survey about nucleophilic additions to aldehydes with quaternary α-centers is presented.
Ring opening/fragmentation of dihydropyrones for the synthesis of homopropargyl alcohols
Tummatorn, Jumreang,Dudley, Gregory B.
, p. 5050 - 5051 (2008/10/09)
Ring-opening/C-C bond cleavage reactions induced by nucleophilic addition of methyl Grignard to 5,6-dihydro-2-pyrone (DHP) triflates 1 furnish homopropargyl alcohols (1 → 2) stereospecifically with respect to the stereochemistry of 1. Carbonyl extrusion from DHP triflates provides a unified and operationally simple strategy for preparing chiral homopropargyl alcohols. Copyright
