56438-69-8Relevant academic research and scientific papers
Chemoenzymatic Total Synthesis of Deoxy-, epi-, and Podophyllotoxin and a Biocatalytic Kinetic Resolution of Dibenzylbutyrolactones
Lazzarotto, Mattia,Hammerer, Lucas,Hetmann, Michael,Borg, Annika,Schmermund, Luca,Steiner, Lorenz,Hartmann, Peter,Belaj, Ferdinand,Kroutil, Wolfgang,Gruber, Karl,Fuchs, Michael
, p. 8226 - 8230 (2019/05/21)
Podophyllotoxin is probably the most prominent representative of lignan natural products. Deoxy-, epi-, and podophyllotoxin, which are all precursors to frequently used chemotherapeutic agents, were prepared by a stereodivergent biotransformation and a biocatalytic kinetic resolution of the corresponding dibenzylbutyrolactones with the same 2-oxoglutarate-dependent dioxygenase. The reaction can be conducted on 2 g scale, and the enzyme allows tailoring of the initial, “natural” structure and thus transforms various non-natural derivatives. Depending on the substitution pattern, the enzyme performs an oxidative C?C bond formation by C?H activation or hydroxylation at the benzylic position prone to ring closure.
Reaction of Aryl and Vinyl Halides with Zerovalent Nickel-Preparative Aspects and the Synthesis of Alnusone
Semmelhack, M.F.,Helquist, Paul,Jones, L.D.,Keller, Leonard,Mendelson L.,et al.
, p. 6460 - 6471 (2007/10/02)
Zerovalent nickel complexes such as bis(1,5-cyclooctadiene)nickel and tetrakis(triphenylphosphine)nickel react rapidly with aryl and vinyl halides to produce the symmetrical coupling products, a low-temperature analogue of the Ullman reaction.The reaction proceeds through oxidative addition of the organic halide to Ni(0), and the reactivity of the Ni(II)intermediates has been examined.Arylnickel halide complexes decompose rapidly to biaryls in DMF.The coupling of simple vinyl halides proceeds with isomerization of the double bond but 3-haloacrylates give efficient co upling with retention of geometry.Cyclizations to form ortho-bridged biaryls are efficient in simple cases (6-, 7-, 8-, 9-, 10-, and 14-membered rings) but fail with an ortho-disubstituted case.The 13-membered meta-bridged cyclic biphenyl, alnusone, is prepared efficiently with the crucial aryl halide coupling to form the ring proceeding in 50percent yield.A side reaction promoted by the presence of protons and with certain ortho-substituted aryl halides is reduction of the aryl halide to the arene.This process can be enhanced by deliberate addition of acid during reaction with Ni(0) and a series of aryl halides underwent succesful reduction.
