The first total synthesis of cyanthiwigins A, C, H and concise synthesis of cyanthiwigin G was achieved from a commonintermediate. A modified formal [4 + 2] cycloaddition was developed to construct the key cis-hydrindanone (A–B). Stereospecific 1,4-addition, alkylation, and ring-closing metathesis were used to build the tricarbocyclic ring system (A–B–C). Various site-selective oxidations were applied
An animalic note: The first total synthesis of the all‐cis nupharamine 2, an alkaloid from beaver castoreum, is based on the stereoselective domino Mannich–Michael reaction of N‐galactosylfurylaldimine to give 1 (Piv=pivaloyl), subsequent conjugate cuprate addition, and stereoselective protonation of the enolate. These reactions are all controlled by the carbohydrate. Protonation of the enolate after
Direct Conversion of Secondary Trimethylsilyl Ethers to Ketones
作者:R. Baker、V. Bhaskar Rao、P. D. Ravenscroft、C. J. Swain
DOI:10.1055/s-1983-30431
日期:——
Studies toward Total Synthesis of Divergolides C and D
作者:Sivappa Rasapalli、Gopalakrishna Jarugumilli、Gangadhara Rao Yarrapothu、James A. Golen、Arnold L. Rheingold
DOI:10.1021/ol400528g
日期:2013.4.5
A facile synthesis of the western segment of divergolides C and D has been developed. Exploratory studies with two disconnections, i.e., C4-C5 vs C5-C6, for elaboration of the ansa bridge to the sterically demanding hexasubstituted naphthalenic aromatic core using a chiral synthon assembled from D-glucose via a stereoselective Johnson orthoester rearrangement Is described. The studies set the stage for the completion of the total synthesis of the biologically important novel ansamycins, divergolides C and D, and their structural congeners.
A free-radical cyclization of .alpha.-bromo acetals leading to tetracyclic 9.beta.-picrasanes
作者:Moonsun Kim、Raymond S. Gross、Hubert Sevestre、Norma K. Dunlap、David S. Watt