Asymmetric Total Syntheses of (−)-Variabilin and (−)-Glycinol
摘要:
Total syntheses of (-)-variabilin and (-)-glycinol have been accomplished, using the catalytic, asymmetric "Interrupted" Feist-Benary reaction (IFB) as the key transformation to introduce both stereogenic centers. A monoquinidine pyrimidinyl ether catalyst affords the IFB products In over 90% ee in both cases. Other key steps include an intramolecular Buohwald-Hartwig coupling and a nickel-catalyzed aryl tosylate reduction.
Total Synthesis of Bryostatins: The Development of Methodology for the Atom-Economic and Stereoselective Synthesis of the Ring C Subunit
作者:Barry M. Trost、Alison J. Frontier、Oliver R. Thiel、Hanbiao Yang、Guangbin Dong
DOI:10.1002/chem.201002898
日期:2011.8.22
for the stereoselective assembly of the ring C subunit were developed. A Pd‐catalyzed tandem alkyne–alkyne coupling/6‐endo‐dig cyclization sequence was explored and successfully pursued in the synthesis of a dihydropyran ring system. Elaboration of this methodology ultimately led to a concise synthesis of the ring C subunit of bryostatins.
苔藓抑素是一个结构复杂的大环内酯类,表现出异常广泛的生物活性。这些分子的有限可用性和结构复杂性使得开发有效的全合成尤为重要。本文描述了我们对苔藓抑素全合成的初步努力,其中开发了用于环 C 亚基立体选择性组装的化学选择性和原子经济方法。在二氢吡喃环系统的合成中探索并成功地探索了Pd 催化的串联炔 - 炔偶联/6- endo - dig环化序列。这种方法的详细说明最终导致了苔藓抑素环 C 亚基的简明合成。
Propylene Glycol Cyclic Sulfate as a Substitute for Propylene Oxide in Reactions with Acetylides
作者:Roderick W. Bates、Tushar B. Maiti
DOI:10.1081/scc-120015819
日期:2003.1.4
Abstract Lithium acetylides react cleanly with propylene glycol cyclicsulfate to give, after acidic hydrolysis, homopropargylic alcohols in good yield. The benzyl and TBDPS protecting groups are stable to these conditions, but the THP, TBS, acetal and orthoester groups are not. The readily available (S)-cyclic sulfate gives the (S)-alcohol without loss of stereochemical integrity.
The second generation synthesis of (+)-pseudodeflectusin (1), a potential antitumor agent, has been achieved. The key synthetic step is the cascade reaction involving Diels-Alder reaction, lactonization, and decarboxylation to give cycloadduct 6 with complete regioselectivity in good yield. We found that NaH is the best base to facilitate the Diels-Alder reaction of hydroxypyrone 7 with alkyne 8. The present synthetic route enables the total synthesis of (+)-1 in only five-steps from the known compounds 7 and 8. (C) 2010 Elsevier Ltd. All rights reserved.
Atom Economical Syntheses of Oxygen Heterocycles via Tandem Palladium-Catalyzed Reactions