N. A. Aksenov, A. The intermediate oxime benzenesulfonate (120) rearranged to furnish the imino ether 122, via the capture of the nitrilium moiety in the intermediate 121 by a neighboring hydroxyl group, as indicated. The scope and generality of the developed protocol has been demonstrated by 19 examples. The resulting nitrilium ion is intercepted by water to form amide 107 (Scheme 40).79. In this sequence, the Beckmann reaction has been effected in a dense and sensitively functionalized skeleton. Wu and Jacobsen report the rearrangement of the α,β-unsaturated azido ketoxime 117 (Scheme 24) with excess TiCl3(OPri) in dichloromethane at room temperature.124 The corresponding caprolactam derivative 118 was obtained in 66% yield (despite competing oxime stereoisomerization). The Application of the Schmidt Reaction and Beckmann Rearrangement to the Synthesis of Bicyclic Lactams: Some Mechanistic Considerations. Please reconnect, https://doi.org/10.1021/acs.orglett.6b01634. Dipak S. Dalal, Dipak R. Patil, Yogesh A. Tayade. not otherwise permitted to reproduce, republish, redistribute, or sell any Supporting Information Katja S. Håheim, Ida T. Urdal Helgeland, Emil Lindbäck, Magne O. Sydnes. Beckmann rearrangement: Thiamine hydrochloride as a remarkable catalyst for one-pot synthesis of amides from ketones. Kengo Hyodo, Genna Hasegawa, Naoki Oishi, Kazuma Kuroda. http://pubs.acs.org/page/copyright/permissions.html, https://doi.org/10.1021/acs.orglett.0c02168, https://doi.org/10.1021/acs.orglett.9b02433, https://doi.org/10.1021/acs.orglett.8b00346, https://doi.org/10.1021/acs.orglett.7b03580, https://doi.org/10.1021/acs.orglett.7b02105, https://doi.org/10.1021/acs.orglett.7b00389, https://doi.org/10.1016/j.tetlet.2020.151859, https://doi.org/10.1007/s41061-020-0285-9, https://doi.org/10.1002/9781119288657.ch12, https://doi.org/10.1016/B978-0-12-817903-1.00002-4, https://doi.org/10.1016/j.tet.2019.04.026, https://doi.org/10.1007/s11172-019-2493-4, https://doi.org/10.1016/j.freeradbiomed.2018.10.425, https://doi.org/10.1016/j.tetlet.2018.09.043, https://doi.org/10.1016/j.ejmech.2018.08.015, https://doi.org/10.1080/00397911.2017.1364767. * Mostly applied for ketoximes. )70, The Beckmann reaction of ketoxime 138 derived from ursolic acid (not shown) furnishes a mixture of the rearrangement and fragmentation products 140 and 141, respectively, in varying amounts depending on the reaction conditions (Scheme 28). The macrocyclic lactone moiety and the two anomeric centers in the pyranose units are particularly noteworthy, as these are sensitive to acid media (normally used for the Beckmann rearrangement). Metal-Free Regioselective Dual C-H Functionalization in a Cascade Fashion: Access to Isocryptolepine Alkaloid Analogues. Organoaluminum-mediated Beckmann Rearrangement (equation 27). 1886, 19, 988–993. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. (Scheme 23. Shun Wang, Yong-Qiang Guo, Zhi-Hui Ren, Yao-Yu Wang, and Zheng-Hui Guan . stream
from the ACS website, either in whole or in part, in either machine-readable form or any other form Zhen Li, Chengtao Fang, Yannan Zheng, Guanyinsheng Qiu, Xiaofang Li, Hongwei Zhou. The Beckmann rearrangement has been reviewed < 60OR(11)1, 88OR(35)1 >, but several developments towards N-alkyl alkanoamides are outlined here.For instance, the one-pot procedure reported by Olah et al. The American Chemical Society holds a copyright ownership interest in any copyrightable Supporting References [1] B. Capuano, I. T. Crosby, E. J. Lloyd, D. A. Taylor , Aust. <<
Applications in drug synthesis:- • The Beckmann rearrangement is also used in the synthesis of 1. Z. Gasanova, G. M. Abakarov, I. V. Aksenova, A. V. Aksenov. This would favor approach by hydride from the top face of (67), whereas in the absence of aluminum the favored approach of hydride is from the bottom face of transition state structure (66). Some modern alternatives involve the use of TsCl and pyridine < … Recent Developments in the C(sp
Visible-Light-Induced Beckmann Rearrangement by Organic Photoredox Catalysis. An analogous reaction involves the treatment of O-methylsulfonyl oxime 113 with 1,7-diazabicyclo-[5.4.0]-undecene (DBU) to give the cyclic imine 114 via an intramolecular SN2 reaction (Scheme 41).82, S. Chandrasekhar, in Comprehensive Organic Synthesis II (Second Edition), 2014. Yields of minor regiomers are shown in parentheses. 3
The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. In the presence of the organoaluminum, the substituent (R) on the chiral center adjacent to nitrogen in (67) is forced to occupy an axial position to relieve the strain created by the steric interaction with aluminum. This may be considered a ‘quasi-Beckmann’ reaction, inasmuch as a nitrone is an N-alkylated oxime, and the reaction leads to a lactam via a Beckmann-type migration.). Copyright © 2020 Elsevier B.V. or its licensors or contributors. -Activated Efficient Beckmann Rearrangement of Ketoximes for Accessing Amides and Lactams. Get article recommendations from ACS based on references in your Mendeley library. @~ (* {d+��}�G�͋љ���ς�}W�L��$�cGD2�Q���Z4 E@�@����� �A(�q`1���D ������`'�u�4�6pt�c�48.��`�R0��)� Nucleophilic substitutions at the nitrogen center of oximes. For permission to reproduce, republish and Elida N. Thobokholt, Enrique L. Larghi, Andrea B. J. Bracca, Teodoro S. Kaufman. Several ingenious modifications of the Beckmann rearrangement have led to novel synthetic protocols with significantly extended applications in complex syntheses.