Participation of sulphonamide nitrogen in the rearrangement of the 2-azabicyclo[2.2.2]octane skeleton: an efficient synthesis of the 6-azabicyclo[3.2.1]octan-4-one system
作者:Andrew B. Holmes、Paul R. Raithby、John Thompson、Andrew J. G. Baxter、John Dixon
DOI:10.1039/c39830001490
日期:——
Treatment of the 2-azabicyclo[2.2.2]oct-5-ene imino Diels–Alder adduct (2) with N-bromosuccinimide in aqueous dimethoxyethane gives the rearranged bromohydrin (4a), whose structure is confirmed by X-ray crystallographic analysis, and which serves as a precursor to the 6-azabicyclo[3.2.1]octane-4-one (7).
Total synthesis of (±)-isoprosopinine B and (±)-desoxoprosopinine
作者:Andrew B. Holmes、John Thompson、Andrew J. G. Baxter、John Dixon
DOI:10.1039/c39850000037
日期:——
The synthesis of the title compounds (10) and (16) in eleven and ten steps respectively from the imine (1) and 2-trimethylsilyloxycyclohexa-1,3-diene (2)via the azabicyclo-octanone (3) and the triol (5) illustrates a new general method for the preparation of the prosopis alkaloids.
An annulation method for the synthesis of alkyl-substituted 6-carbomethoxy-2-pyridones
作者:Yu Zhang、Brad M. Loertscher、Steven L. Castle
DOI:10.1016/j.tet.2009.06.006
日期:2009.8
A protocol for the synthesis of 5-alkyl and 3,5-dialkyl-6-carbomethoxy-2-pyridones was devised. Key steps include a Mannich reaction, acylation of a tosylamine, and a PPh3/TiCl4-promoted intramolecular Reformatsky-type reaction with a thioester as the electrophile. The latter process typically afforded a vinylogous thiocarbamate via elimination of water rather than the Dieckmann-type product which would have resulted from elimination of the thiol. However, the Dieckmann-type ketone product was obtained in one instance. Subsequent elimination of the tosyl group and desulfurization completed the pyridone synthesis. (C) 2009 Elsevier Ltd. All rights reserved.
Lewis acid-mediated [3+2] cycloaddition of allyltriisopropylsilane to N-sulfonyl aldimines
BF3. OEt2-mediated [3+2] cycloaddition of allyltriisopropylsilane to N-sulfonyl aldimine afforded silyl substituted pyrrolidines in good yields. Excellent cis selectivity was observed with aromatic aldimines. (C) 2001 Elsevier Science Ltd. All rights reserved.