Oxyboration with and without a Catalyst: Borylated Isoxazoles via B–O σ-Bond Addition
摘要:
Herein we report an oxyboration reaction with activated substrates that employs B-O sigma bond additions to C-C pi bonds to form borylated isoxazoles, which are potential building blocks for drug discovery. Although this reaction can be effectively catalyzed by gold, it is the first example of uncatalyzed oxyboration of C-C pi bonds by B-O sigma bonds-and only the second example that is catalyzed. This oxyboration reaction is tolerant of groups incompatible with alternative lithiation/borylation and palladium-catalyzed C-H activation/borylation technologies for the synthesis of borylated isoxazoles.
iron(III)-catalyzed synthesis of substituted β-chlorovinyl ketones and α,β-alkynyl ketones from terminal and silyl-substituted alkynes with acidchlorides, respectively, is described. This method features easily available starting materials, a cheap and non-toxic catalyst, simple manipulation and mild reaction conditions. Evidence shows that the catalytic addition of the acidchloride to a terminal alkyne
common oxidization to carbonyl group in secondary propargyl alcohols was successfully developed to form 2-benzyl substituted isoquinoline N-oxides by a Rhodium-catalyzed C−H activation and annulation cascade, in which moderate to excellent yields (up to 92%) could be obtained under mild reaction conditions, along with good regioselectivity, broad generality and applicability.
Laccase‐mediated Oxidations of Propargylic Alcohols. Application in the Deracemization of 1‐arylprop‐2‐yn‐1‐ols in Combination with Alcohol Dehydrogenases
studied usingalcoholdehydrogenases such as the one from Ralstonia species overexpressed in E. coli or the commercially available evo‐1.1.200, allowing the access to both alcohol enantiomers mostly with complete conversions and variable selectivities depending on the aromatic pattern substitution (97–>99 % ee). To demonstrate the compatibility of the laccase‐mediated oxidation and the alcohol dehydrogenase‐catalyzed
Covalent Adaptable Networks with Tunable Exchange Rates Based on Reversible Thiol–yne Cross‐Linking
作者:Niels Van Herck、Diederick Maes、Kamil Unal、Marc Guerre、Johan M. Winne、Filip E. Du Prez
DOI:10.1002/anie.201912902
日期:2020.2.24
adaptable networks (CANs) relies on the ability to trigger the rearrangement of bonds within a polymer network. Simple activated alkynes are now used as versatile reversible cross-linkers for thiols. The click-like thiol-yne cross-linking reaction readily enables network synthesis from polythiols through a double Michael addition with a reversible and tunable second addition step. The resulting thioacetal
A new application of the hypervalentiodine reagent phenyliodine(III)bis(trifluoroacetate) (PIFA) has been developed for the construction of a series of N, O, S-containing heterocycle-fused quinolinone derivatives in a general and efficient way. An alternative approach to the formation of these novel tricyclic heterocycles by a PIFA mediated aryl–heteroaryl coupling reaction is also presented.