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The intriguing structural complexity and bioactivities of the alkaloids have long attracted much attention. Herein, we report the first and enantioselective total synthesis of alkaloid dapholdhamine B and its lactone derivative. The chemical structure of dapholdhamine B contains a unique aza-adamantane core skeleton and eight contiguous stereocenters, including three contiguous fully substituted stereocenters, which present a formidable synthetic challenge. This concise approach used to achieve the first synthesis of an aza-adamantane natural product features a vinylogous Mannich reaction, an optimized α-bromo-α,β-unsaturated ketone synthesis, a substrate-dependent intramolecular aza-Michael addition, a key annulation via amide activation, an S2'-type lactonization, and a facile Horner-Wadsworth-Emmons reaction that converts the hemiacetal moiety to the corresponding homologated carboxylic acid.
This article was published in the following journal.
Name: Journal of the American Chemical Society
A convergent, stereocontrolled total synthesis of psymberin, an architecturally complex marine antitumor agent, has been achieved in 27 steps from the known aldehyde 8. Highlights of this synthesis in...
The first total synthesis of the potent antibiotic Berkeleylactone A is described in 10 steps with an overall yield of 9.5%. A key step of our concise route is a late stage, highly diastereoselective,...
Concise, divergent total syntheses of five bioactive illudalane sesquiterpenes have been achieved. Our synthesis features an intermolecular [2+2+2] cycloaddition, and a lactone-directed aromatic C-H o...
An efficient synthesis of pyridopyrazine-1,6-dione -secretase modulators (GSMs) is described. Our route features the construction of a crystalline lactone intermediate via a selective palladium-cat...
A method for the direct oxidation of various N-aryl tetrahydroisoquinolines and isoindolines to the corresponding lactams using α-angelica lactone as a catalyst was developed. The utility of the meth...
The aim of this study is to evaluate the safety and effectivity of Ginkgo diterpene lactone meglumine injection tn the treatment of acute ischemic stroke
This study evaluates the addition of Ginkgo Diterpene Lactone Meglumine Injection to aspirin in the treatment of acute ischemic stroke.Half of patient will receive Ginkgo Diterpene Lactone...
Cholesterol is the precursor of glucocorticoids, mineralocorticoids and sex steroids. Both adrenal and non-adrenal (ovarian + testicular) all steroid hormones are primarily synthesized usi...
The purposes of this study include: - Determination of the change in clearance of topotecan and topotecan lactone between day 1 and day 14 for patients receiving treatment with p....
Collagen synthesis is depressed systemically in the immediate postoperative period. Arginine, zinc and vitamin C impact collagen synthesis. The aim of this study is to investigate the eff...
Distention of KIDNEY with the presence of PUS and suppurative destruction of the renal parenchyma. It is often associated with renal obstruction and can lead to total or nearly total loss of renal function.
A subtype of von Willebrand disease that results from a total or near total deficiency of VON WILLEBRAND FACTOR.
A procedure in which total right atrial or total caval blood flow is channeled directly into the pulmonary artery or into a small right ventricle that serves only as a conduit. The principal congenital malformations for which this operation is useful are TRICUSPID ATRESIA and single ventricle with pulmonary stenosis.
Catalyzes the hydrolysis of the gamma lactone, dehydroascorbate, to diketogulonate.
A plant genus of the family ASTERACEAE. Members contain scandenolide (a sesquiterpene lactone) and germacranolides.