1909-79-1Relevant articles and documents
C-O Bond Activation as a Strategy in Palladium-Catalyzed Cross-Coupling
Becica, Joseph,Leitch, David C.
, p. 641 - 646 (2020/12/14)
The activation of strong C-O bonds in cross-coupling catalysis can open up new oxygenate-based feedstocks and building blocks for complex-molecule synthesis. Although Ni catalysis has been the major focus for cross-coupling of carboxylate-based electrophiles, we recently demonstrated that palladium catalyzes not only difficult C-O oxidative additions but also Suzuki-Type cross-couplings of alkenyl carboxylates under mild conditions. We propose that, depending on the reaction conditions, either a typical Pd(0)/(II) mechanism or a redox-neutral Pd(II)-only mechanism can operate. In the latter pathway, C-C bond formation occurs through carbopalladation of the alkene, and C-O cleavage by β-carboxyl elimination. 1 Introduction 2 A Mechanistic Challenge: Activating Strong C-O Bonds 3 Exploiting Vinylogy for C-Cl and C-O Oxidative Additions 4 An Alternative Mechanism for Efficient Cross-Coupling Catalysis 5 Conclusions and Outlook.
Simple Routes to Sarkomycin
Kodpinid, Montree,Siwapinyoyos, Tiwa,Thebtaranonth, Yodhathai
, p. 4862 - 4865 (2007/10/02)
Two synthetic routes to sarkomycin (6) are demonstrated.The first involves a 3-carbon annelation to form the spirocyclopentenone (2) followed by regiospecific γ-alkylation and subsequent manipulation of the side chain in 15 to give the sarkomycin ester adduct 18.The second route employs the itaconate-anthracene adduct 20 as the C-5 synthon in a tandem Michael addition-Dieckmann condensation between the anion derived from 20 and methyl acrylate.The reaction furnishes the diester 22, which, upon selective decarboxylation, gives rise to the sarkomycin precursors 18 and 23 (1:3).Flash vacuum pyrolysis of either isomer 18 or 23 yields (+/-)-sarkomycin ester 7 which is then hydrolyzed to the acid 6.
