98331-07-8Relevant academic research and scientific papers
Rationalisation of patterns of competing reactivity by x-ray structure determination: Reaction of isomeric (benzyloxythienyl)oxazolines with a base
Aitken, R. Alan,Harper, Andrew D.,Slawin, Alexandra M. Z.
, (2021/12/27)
Three isomeric (benzyloxythienyl)oxazolines 9, 11 and 13 have been prepared and are found, upon treatment with a strong base, to undergo either Wittig rearrangement or intramolecular attack of the benzylic anion on the oxazoline function to give products derived from cleavage of the initially formed 3-aminothienofuran products. This pattern of reactivity is directly linked to the distance between the two reactive groups as determined by X-ray diffraction, with the greatest distance in 11 leading to exclusive Wittig rearrangement, the shortest distance in 13 giving exclusively cyclisation-derived products, and the intermediate distance in 9 leading to both processes being observed. The corresponding N-butyl amides were also obtained in two cases and one of these undergoes efficient Wittig rearrangement leading to a thieno[2,3-c]pyrrolone product.
The Scope and Limitations of Carboxamide-Induced β-Directed Metalation of 2-Substituted Furan, Thiophene, and 1-Methylpyrrole Derivatives Application of the Method of Syntheses of 2,3-Disubstituted Thiophenes and Furans
Carpenter, Andrew J.,Chadwick, Derek J.
, p. 4362 - 4368 (2007/10/02)
The effects of change of solvent, metalating agent, reaction time, and reaction temperature on the lithiation of N,N-diethylthiophene-2-carboxamide and of the N-tert-butyl-2-carboxamide derivatives of furan, thiophene, and 1-methylpyrrole are explored, and optimum conditions are established for ring β-directed metalation.The tertiary carboxamido group is less effective in this context than the secondary amide function and appears to be of limited value in these heteroaromatic systems.The high metalation levels achievable with the furan and thiophene secondary amides allow high-yielding syntheses (through reaction of the lithiated intermediates with a wide range of electrophiles) of otherwise inaccessible 2,3-disubstituted derivatives.The synthetical value of the methodology appears to be limited only by the forcing conditions required for amide hydrolysis.
