Xn:Harmful;106-63-8Relevant articles and documents
Exploring the scope of the 29G12 antibody catalyzed 1,3-dipolar cycloaddition reaction
Toker, Jonathan D.,Tremblay, Martin R.,Yli-Kauhaluoma, Jari,Wentworth, Anita D.,Zhou, Bin,Wentworth Jr., Paul,Janda, Kim D.
, p. 7810 - 7815 (2005)
29G12 is a murine monoclonal antibody programmed to catalyze the regio- and enantioselective 1,3-dipolar cycloaddition reaction between 4-acetamidobenzonitrile N-oxide 1a and N,N-dimethylacrylamide 2a (Toker, J. D.; Wentworth, P., Jr.; Hu, Y.; Houk, K. N.; Janda, K. D. J. Am. Chem. Soc. 2000, 122, 3244). Given the unique nature of 29G12 as a protein biocatalyst for this chemical reaction, we have investigated both the substrate specificity and mechanistic parameters of the 29G12-catalyzed process. These studies have shown that while 29G12 is specific for its dipole substrate Ia, the antibody is highly promiscuous with respect to the dipolarophiles it can process. 29G12 accepts a bulky hydrophobic dipolarophile cosubstrate, with rates of product formation up to 70-fold faster than with the original substrate 2a. In all cases, the respective isoxazoline products are produced with exquisite regio- and stereochemical control (78-98% ee). Comparison between the steady-state kinetic parameters from the 29G12-catalyzed reaction of 1a with the most efficient versus the original dipolarophile cosubstrate (2m and 2a, respectively), reveals that while the effective molarities (EM)s are almost identical (EM (2m) 26 M; EM(2a) 23 M), the affinity of 29G12 for the larger dipolarophile 2m is more than 1 order of magnitude higher than for 2a [Km(2m) 0.44 ± 0.04 mM; Km(2a) 5.8 ± 0.4 mM]. Furthermore, when 2m is the cosubstrate, the affinity of 29G12 for its dipole 1a is also greatly improved [Km(1a) 0.82 ± 0.1 mM compared to Km(1a) 3.4 ± 0.4 mM when 2a is the cosubstrate]. An analysis of the temperature dependence of the 29G12-catalyzed reaction between 1a and 2m reveals that catalysis is achieved via a decrease in enthalpy of activation (ΔΔH? 4.4 kcal mol-1) and involves a large increase in the entropy of activation (ΔΔS? 10.4 eu). The improved affinity of 29G12 for the nitrile oxide Ia in the presence of 2m, coupled with the increase in ΔΔS? during the 29G12-catalyzed reaction between 1a and 2m supports the notion of a structural reorganization of the active site to facilitate this antibody-catalyzed reaction.
Acid- And base-switched palladium-catalyzed γ-C(sp3)-H alkylation and alkenylation of neopentylamine
Zhang, Jinquan,Zhang, Shuaizhong,Zou, Hongbin
supporting information, p. 3466 - 3471 (2021/05/31)
The functionalization of remote unactivated C(sp3)-H and the reaction selectivity are among the core pursuits for transition-metal catalytic system development. Herein, we report Pd-catalyzed γ-C(sp3)-H-selective alkylation and alkenylation with removable 7-azaindole as a directing group. Acid and base were found to be the decisive regulators for the selective alkylation and alkenylation, respectively, on the same single substrate under otherwise the same reaction conditions. Various acrylates were compatible for the formation of C(sp3)-C(sp3) and C(sp3)-C(sp2) bonds. The alkenylation protocol could be further extended to acrylates with natural product units and α,β-unsaturated ketones. The preliminary synthetic manipulation of the alkylation and alkenylation products demonstrates the potential of this strategy for structurally diverse aliphatic chain extension and functionalization. Mechanistic experimental studies showed that the acidic and basic catalytic transformations shared the same six-membered dimer palladacycle.
BLOCK POLYMER, COSMETIC COMPOSITION COMPRISING IT AND COSMETIC TREATMENT PROCESS
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, (2010/02/17)
A block polymer containing, in a block with a Tg greater than 20° C., at least one monomer of formula (I): The invention also relates to a cosmetic composition comprising the block polymer in a cosmetically acceptable medium, and also to a cosmetic process for treating keratin materials using the composition, and most particularly to a process for making up the lips.
