135884-31-0Relevant articles and documents
Synthesis and structural characterization of a trispyrrole iron(II) complex K(dme)4[tpaMesFe] and application in nitrous oxide dependent coupling reactions
Weidauer, Maik,Irran, Elisabeth,Enthaler, Stephan
, p. 1 - 4 (2015)
A new synthetic route to the trispyrrole iron(II) complex {K(dme)4[tpaMesFe]} was established starting from BOC-protected pyrrol via synthesis of the corresponding boronic acid, cross-coupling reaction, deprotection, triple Mannich reaction, a deprotonation and finally a salt metathesis. The complex was characterized and applied in iron-catalyzed coupling reactions. In more detail, with catalytic amounts of K(dme)4[tpaMesFe] the homo-coupling of aromatic Grignard reagents as well as the hetero-coupling of aromatic Grignard reagents were feasible. Noteworthy, to force the reaction nitrous oxide was added to realize yields up to 93% at mild reaction conditions.
Direct selection for catalysis from combinatorial antibody libraires using a boronic acid probe: Primary amide bond hydrolysis
Gao, Changshou,Lavey, Brian J.,Lo, Chih-Hung L.,Datta, Anita,Wentworth Jr., Paul,Janda, Kim D.
, p. 2211 - 2217 (1998)
This report describes a joint hybridoma and combinatorial antibody library approach to elicit catalysts for primary amide bond hydrolysis. By immunization with a trigonal boronic acid hapten 3a and construction of a Fab (antigen-binding fragment) library, a diastereoselective catalyst for hydrolysis of the tripeptide primary amide substrate la was selected. In contrast, no antibody catalyst was isolated by standard hybridoma methods of monoclonal antibody production following immunizations with hapten 3a. The active Fab, BL25, obeys Michaelis-Menten kinetic behavior (k(cat)/k(uncat) ca. 4 x 104, K(m) = 150 μM) and is competitively inhibited by a boronic acid hapten analog 3b (K(i) = 9 μM). Kinetic and binding studies both point to Fab selection of a hydrated tetrahedral anionic form of the boronic acid hapten 3a which serves to mimic the putative transition state 4 for catalysis of water addition to the primary amide bond. Fab-BL25 exhibits exquisite substrate selectivity, as a methyl ester analog of 1a is not accepted as a substrate. This work emphasises the power of the direct selection strategy when linked to screening of antibody combinatorial libraries and discloses the utility of boronic acids as haptens in acyl transfer processes.
Lamellarin-inspired potent topoisomerase I inhibitors with the unprecedented benzo[g][1]benzopyrano[4,3-b]indol-6(13H)-one scaffold
Fukuda, Tsutomu,Nanjo, Yusuke,Fujimoto, Masahiro,Yoshida, Kenyu,Natsui, Yuko,Ishibashi, Fumito,Okazaki, Fumiyasu,To, Hideto,Iwao, Masatomo
, p. 265 - 277 (2019/01/04)
A new class of topoisomerase I inhibitors containing the unprecedented benzo[g][1]benzopyrano[4,3-b]indol-6(13H)-one (abbreviated as BBPI) ring system have been developed based on structure-activity relationship studies of the cytotoxic marine alkaloid la
Stereochemistry and Mechanism of Undecylprodigiosin Oxidative Carbocyclization to Streptorubin B by the Rieske Oxygenase RedG
Withall, David M.,Haynes, Stuart W.,Challis, Gregory L.
supporting information, p. 7889 - 7897 (2015/07/02)
The prodiginines are a group of specialized metabolites that share a 4-methoxypyrrolyldipyrromethene core structure. Streptorubin B is a structurally remarkable member of the prodiginine group produced by Streptomyces coelicolor A3(2) and other actinobacteria. It is biosynthesized from undecylprodigiosin by an oxidative carbocyclization catalyzed by the Rieske oxygenase-like enzyme RedG. Undecylprodigiosin derives from the RedH-catalyzed condensation of 2-undecylpyrrole and 4-methoxy-2, 2′-bipyrrole-5-carboxaldehyde (MBC). To probe the mechanism of the RedG-catalyzed reaction, we synthesized 2-(5-pentoxypentyl)-pyrrole, an analogue of 2-undecylpyrrole with an oxygen atom next to the site of C-C bond formation, and fed it, along with synthetic MBC, to Streptomyces albus expressing redH and redG. This resulted in the production of the 6′-oxa analogue of undecylprodigiosin. In addition, a small amount of a derivative of this analogue lacking the n-pentyl group was produced, consistent with a RedG catalytic mechanism involving hydrogen abstraction from the alkyl chain of undecylprodigiosin prior to pyrrole functionalization. To investigate the stereochemistry of the RedG-catalyzed oxidative carbocyclization, [7′-2H](7′R)-2-undecylpyrrole and [7′-2H](7′S)-2-undecylpyrrole were synthesized and fed separately, along with MBC, to S. albus expressing redH and redG. Analysis of the extent of deuterium incorporation into the streptorubin B produced in these experiments showed that the pro-R hydrogen atom is abstracted from C-7′ of undecylprodigiosin and that the reaction proceeds with inversion of configuration at C-7′. This contrasts sharply with oxidative heterocyclization reactions catalyzed by other nonheme iron-dependent oxygenase-like enzymes, such as isopenicillin N synthase and clavaminate synthase, which proceed with retention of configuration at the carbon center undergoing functionalization. (Chemical Equation Presented).
