The aminomethylpolystyrene-supported (diacetoxyiodo)benzene reagents 4a and 4b were prepared for the first time. Using these reagents several hydroquinones and phenols can be oxidized to the corresponding quinones. Spirocyclization of phenylacetic acid and of N-protected tyrosine derivatives could also be accomplished.
Stereoselectivity Control by Oxaspiro Rings during Diels−Alder Cycloadditions to Cross-Conjugated Cyclohexadienones: The <i>Syn</i> Oxygen Phenomenon
作者:Katsuo Ohkata、Yukiko Tamura、Brandon B. Shetuni、Ryukichi Takagi、Wataru Miyanaga、Satoshi Kojima、Leo A. Paquette
DOI:10.1021/ja047027t
日期:2004.12.1
parameters were determined for the cycloaddition of 1a and 2a to cyclopentadiene. The rate acceleration profile of solvents was in the order CF(3)CH(2)OH >> CH(3)CN approximately CH(2)Cl(2) for the production of 9a from 1a and CF(3)CH(2)OH >> CH(2)Cl(2) > CH(3)CN for the production of 21a from 2a, respectively. This spread in polarity had no major impact on product distribution, a phenomenon also reflected
The indirect (“ex-cell”) electrochemical synthesis of benzoxazoles from imines using a redox mediator based on the iodine(I)/iodine(III) redox couple is reported. Tethering the redox-active iodophenyl subunit to a tetra-alkylammonium moiety allowed for anodic oxidation to be performed without supporting electrolyte. The mediator salt can be easily recovered and reused. Our “ex-cell” approach toward
Various practical methods for the selective C−Hfunctionalization of the ortho and recently also of the meta position of an arene have already been developed. Following our recent development of the directing‐group‐assisted para C−Hfunctionalization of toluene derivatives, we herein report the first remote para C−Hfunctionalization of phenol derivatives by using a recyclable silicon‐containing biphenyl‐based
Oxidation with hypervalent iodine reagents. Part II: Novel cyclohexadienones as precursors for the synthesis of anthraquinones
作者:Anthony S. Mitchell、Richard A. Russell
DOI:10.1016/s0040-4020(97)00110-5
日期:1997.3
2,4-cyclohexadienones, 2,5-cyclohexadienones or mixtures of isomers, depending on the substrate being oxidized. Annulation of these cyclohexadienones with the anion of 3-cyanophthalide afforded anthraquinones in high yields.