The first total synthesis and structural determination of actinopyrone A
摘要:
Actinopyrone A (1) has been synthesized by using our developed remote stereoinduction, Kocienski olefination, Horner-Wadsworth-Emmons olefination, and reductive de-conjugation of the vinylpyrone. A concise method of O-methylation to obtain the gamma-pyrone has also been established. (c) 2006 Elsevier Ltd. All rights reserved.
biosynthesis. However, in the case of pellasoren, one chiral center was not predicted correctly. The absolute configuration was verified by total synthesis, which also demonstrated that stereoselective protonations can be successfully applied to natural products synthesis.
<i>syn</i>-Selective Kobayashi Aldol Reaction Using Acetals
作者:Hiroyuki Tsukada、Yuki Mukaeda、Seijiro Hosokawa
DOI:10.1021/ol303519y
日期:2013.2.1
The Kobayashi aldol reaction has been used to construct anti-aldol products by remote stereoinduction. Since the product of the Kobayashi aldol reaction has a typical polyketide structure, this reaction has been applied to the total synthesis of natural products. By varying this reaction, it was found that the reaction with acetals in the presence of Lewis acid proceeded to give syn adducts in high
Stereoselective acylation of the E,E-vinylketene silyl N,O-acetal possessing a chiral auxiliary has been achieved by using acid anhydrides and SnCl4. Acid anhydrides having alkyl chains gave the adducts in excellent stereoselectivity. The formal synthesis of khafrefungin has been accomplished by the methodology.
Stereoselective alkylation of the vinylketene silyl N,O-acetal possessing a chiral auxiliary has been achieved by using activated alkyl halides including allyl iodides, benzyl iodides, and propargyl iodide with Ag(I) ion in the presence of BF3·OEt2. The reaction proceeded to give reduced polyketides in high stereoselectivity. The synthesis of mycocerosic acid, a component of the cell envelope of Mycobacterium
Stereoselective bromination of the E,E-vinylketene silyl N,O-acetal possessing a chiral auxiliary has been achieved and applied to introduction of heteroatom at γ-position of α,β-unsaturated imide. The reactions proceeded in high stereoselectivity. Totalsynthesis of pellasoren A, an antitumor propionate from the myxobacteriun Sorangium cellulosum, has been accomplished in short steps by this methodology