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.
An efficient synthesis of 2,5-disubstitutedfurans directly from alkynyl ketones has been developed via tandem gold(I)-catalyzed isomerization of alkynyl ketones to allenyl ketones and cycloisomerization. The key to the success of this chemistry is the use of a biphenyl-2-ylphosphine ligand featuring a critical remote tertiary amino group.
The present work describes the application of nano CoCuFe2O4 toward the coupling reaction of acyl chlorides with terminalalkynes. By this catalytic system, ynone derivatives were formed in high yields via a palladium-free strategy. This protocol avoids the use of phosphine ligands as well as toxic CO sources. Recovery of catalyst by employing an external magnetic field and its reuse up to 9 consecutive
本工作描述了纳米CoCuFe 2 O 4在酰基氯与末端炔烃的偶联反应中的应用。通过该催化体系,通过无钯策略以高收率形成了炔酮衍生物。该方案避免使用膦配体以及有毒的CO源。通过使用外部磁场来回收催化剂及其重复使用,多达9个连续试验证实了该催化系统的坚固性。
Synthesis of 4-(Trifluoromethyl)cyclopentenones and 2-(Trifluoromethyl)furans by Reductive Trifluoroacetylation of Ynones
作者:Tianyuan Zhang、Hirofumi Maekawa
DOI:10.1021/acs.orglett.7b03302
日期:2017.12.15
bond formation by magnesium-promoted reduction is ethyl trifluoroacetate, which has been rarely used as a fluorine-containing carbon source, especially to electron-deficient carbon atoms in organic synthesis.
A facile and efficient synthesis of 1,3-diketones was developed by the gold(I)-catalyzed regioselective hydration of ynones at room temperature. This methodology employed 2.5 mol% of PPh3AuCl and 3 mol% of AgOTf as a simple catalytic system without any special phosphine ligand and was compatible with a wide range of substrates, giving rise to 1,3-diaryl, 1-alkyl-3-aryl-, and 1,3-dialkyl-1,3-diketones