Preparation of enol ester epoxides and their ring-opening to α-silyloxyaldehydes
作者:Gregory K. Friestad、Gopeekrishnan Sreenilayam、Joseph C. Cannistra、Luke M. Slominski
DOI:10.1016/j.tetlet.2012.06.142
日期:2012.9
The Z-selective ruthenium-catalyzed addition of aromatic carboxylic acids to alkynes was followed by dioxirane epoxidation to furnish enolesterepoxides with cis configuration. Upon treatment of enolesterepoxides with tert-butyldimethylsilyl triflate in the presence of 2,6-lutidine, synthetically useful α-silyloxyaldehydes were obtained. This novel transformation was facilitated by microwave irradiation
The influence of α-coordinating groups of aldehydes on <i>E</i>/<i>Z</i>-selectivity and the use of quaternary ammonium counter ions for enhanced <i>E</i>-selectivity in the Julia–Kocienski reaction
Modified reaction conditions for improved E-selectivity of olefins in the Julia–Kocienski reaction of aldehydes having α-coordinating substituents are demonstrated. The chelating groups in aldehydes are expected to stabilize the syn-transition state with metal ions, whereas the weakly coordinating quaternary ammonium ions are devoid of all possible chelating interactions to enhance E-selectivity. A
A synthesis of (+)-xylogiblactone A has been achieved from t-butyl 2-methylbuta-2,3-dienoate in a linear three-step sequence. The key elements of the synthesis include a kinetic resolution of racemic 2-silyoxyaldehyde through the allenoate γ-addition to yield the γ-adduct as a single isomer and the subsequent gold catalysis to form the butenolide core. For a general method, the kinetic resolution of
Degradation of aldehydes to one carbon lower homologs has been achieved by using a mixture of N-methylmorpholine, N-methylmorpholine N-oxide, a catalytic amount of OsO4 and NaIO4 in a mixture of acetone/H2O.
通过在丙酮/ H 2 O的混合物中使用N-甲基吗啉,N-甲基吗啉N-氧化物,催化量的OsO 4和NaIO 4的混合物,已将醛降解为一个低碳同系物。
A simple and practical method for the stereoselective synthesis of (Z)-1-iodo-1-alkenes from 1,1-diiodo-1-alkenes
Treatment of the 1,1-diiodo-1-alkenes 8, prepared from the corresponding aldehydes with CI4/PPh3, with ZnCu/AcOH in THF–MeOH gave the (Z)-1-iodo-1-alkenes 9, selectively, in good yields.