220329-77-1Relevant academic research and scientific papers
Planar Chirality: Synthesis and Transannular Reactions of Unsaturated Optically Active Azoninones Bearing E-Olefins
Sudau, Alexander,Muench, Winfried,Nubbemeyer, Udo,Bats, Jan W.
, p. 1710 - 1720 (2000)
The zwitterionic aza-Claisen rearrangement of optically active trans 4-silyloxy-2-vinylpyrrolidines and carboxylic acid fluoride generated nine-membered ring lactams with high yields. The reaction proceeded with an almost complete 1,4-chirality transfer and the exclusive generation of the E-double bond in the medium sized rings to cause additional planar chiral information. The initially formed azoninones were characterized by a pS-arrangement of the olefin with respect to the ring. The rather kinetically stable conformation underwent a flipping of the double bond to give the pR-azoninones as the thermodynamically stable products. The planar diastereomers were subjected to regio- and diastereoselective transannular ring contractions to give indolizidinones. The stereochemical outcome was strongly dependent from the planar chiral information of the double bond and the lactam unit. The so-formed optically active bicycles bearing a defined substitution pattern should serve as versatile building blocks in alkaloid synthesis.
Improved syntheses of cyanuric fluoride and carboxylic acid fluorides
Gross, Steffen,Laabs, Stephan,Scherrmann, Andreas,Sudau, Alexander,Zhang, Nong,Nubbemeyer, Udo
, p. 711 - 714 (2007/10/03)
Cyanuric fluoride (2) is one of the most popular fluorinating agents in organic chemistry. The title compound could be prepared in a 50 to 100 g scale by means of a chlorine fluorine exchange, the process was characterized by a simple preparation procedure, cheap reactants and a low time exposure. Carboxylic acids were converted into the corresponding acid fluorides 4a-g using cyanuric fluoride. A non-aqueous work-up led to high yields on synthesizing a range of functionalized acid fluorides. Wiley-VCH Verlag GmbH, 2000.
