87143-16-6Relevant academic research and scientific papers
Silylformylation - Fluoride-assisted aryl migration of acetylenic derivatives in a versatile approach to the synthesis of polyfunctionalised compounds
Aronica, Laura Antonella,Raffa, Patrizio,Valentini, Giulia,Caporusso, Anna Maria,Salvadori, Piero
, p. 1845 - 1851 (2007/10/03)
Polyfunctionalised aldehydes and dihydropyrans are prepared from easily available functionalised 1-alkynes through a two-step silylformylation/aryl migration sequence. The silylformylation process is performed under mild experimental conditions and affords the corresponding β-silylalkenals in high yields. The fluoride-promoted migration step occurs instantaneously with quantitative conversion. The chemo-, regio- and stereoselectivity can be modulated according to the nature and the position of the functional group on the acetylene precursors. When a good leaving group is present in the ω position of the aliphatic chain of the alkyne a cyclisation product is obtained, while α,β-unsaturated aldehydes are generated from propargylic tosylamides. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Highly Enantioselective Intermolecular Cu(I)-Catalyzed Cyclopropanation of Cyclic Enol Ethers. Asymmetric Total Synthesis of (+)-Quebrachamine
Temme, Oliver,Taj, Shabbir-Ali,Andersson, Pher G.
, p. 6007 - 6015 (2007/10/03)
A set of cyclic enol ethers derived from 2,3-dihydrofuran 35 and 3,4-dihydropyran 8 with a varying substitution pattern at the olefinic system were synthesized. Evans's ligand 5 with Cu(I)OTf was found to be an effective catalyst in the cyclopropanation reaction between cyclic enol ethers 14, 19, 28-31, and 33 and ethyl diazoacetate 6 to give diastereoselectivities up to exo/endo = 95:5 and enantioselectivities higher than 95% in nearly all cases. Because of the selective building of a quarternary carbon center and good yields in the formation of bicyclic structures 34c-h, the reaction was used as a key step in the asymmetric synthesis of (+)-quebrachamine 7, an indole alkaloid of the Aspidosperma family. After acid-induced ring opening of bicyclic compound 34f to lactone 40 followed by LiAlH4 reduction to the masked aldehyde 41, a reaction with tryptamine gave intermediate 42. This alcohol was efficiently converted into the indole alkaloid (+)-quebrachamine 7 in an overall yield of 37% starting from the chiral synthon 34f. Moreover it revealed the absolute configuration of the quarternary center of the cyclopropanation product 34f to be S.
Acyl and Sulfonyl Isocyanates ib β-Lactam Synthesis
Barrett, Anthony G. M.,Betts, Michael J.,Fenwick, Ashley
, p. 169 - 175 (2007/10/02)
The preparation of β-lactams from the reactions of several acyl and sulfonyl activated isocyanates with alkenes was studied.Three compounds, (2,2,2-trichloroethoxy)sulfonyl, 2,2,2-trichloroethane sulfonyl, and trifluoroacetyl isocyanates, were shown to be
