Total Synthesis and Structural Elucidation of Azaspiracid-1. Construction of Key Building Blocks for Originally Proposed Structure
作者:K. C. Nicolaou、Petri M. Pihko、Federico Bernal、Michael O. Frederick、Wenyuan Qian、Noriaki Uesaka、Nicole Diedrichs、Jürgen Hinrichs、Theocharis V. Koftis、Eriketi Loizidou、Goran Petrovic、Manuela Rodriquez、David Sarlah、Ning Zou
DOI:10.1021/ja0547477
日期:2006.2.1
required for the totalsynthesis of the proposedstructure of azaspiracid-1 (1a) are described. Key steps include a TMSOTf-induced ring-closing cascade to form the ABC rings of tetracycle 65, a neodymium-catalyzed internal aminal formation for the construction of intermediate 98, and a Nozaki-Hiyama-Kishi coupling to assemble the required carbon chain of fragment 100. The synthesized fragments, obtained stereoselectively
Synthetic studies of GKK1032s: the asymmetric synthesis of the decahydrofluorene skeleton via a novel cyclization of silyl enol ether and sequential retro Diels–Alder and intramolecular Diels–Alder reactions
decahydrofluorene skeleton of GKK1032s. The C-ring was constructed by intramolecular cyclization reaction between a chiral epoxide and silyl enol ether, and the dienophile moiety was introduced concurrently. In addition, the AB-rings were stereoselectively constructed using novel sequential retro Diels–Alder (DA) and intramolecularDiels–Alder (IMDA) reactions. Several further modifications of the IMDA adduct were
Chemoenzymatic Synthesis of the Polyketide Macrolactone 10-Deoxymethynolide
作者:Courtney C. Aldrich、Lakshmanan Venkatraman、David H. Sherman、Robert A. Fecik
DOI:10.1021/ja0504340
日期:2005.6.1
the natural product 10-deoxymethynolide. A steady-state kinetic analysis of the hexaketidechain intermediate with Pik TE was done. A preliminary substrate specificity study with unnatural hexaketide analogues was accomplished, demonstrating the importance of total synthesis in obtaining access to advanced polyketide intermediates. The results show the sensitivity of Pik TE to minor substrate modifications
聚酮合酶衍生的皮克霉素硫酯酶 (Pik TE) 具有独特的催化 12 和 14 元大环内酯环化的能力。在这项研究中,天然六酮链延长中间体作为其 N-乙酰半胱胺 (NAC) 硫酯的全合成已经实现,其与 Pik TE 的反应证明了 Pik TE 催化其大环内酯化成天然产物 10-脱氧甲炔内酯。使用 Pik TE 对六酮链中间体进行稳态动力学分析。完成了对非天然六酮化合物类似物的初步底物特异性研究,证明了全合成在获得高级聚酮化合物中间体方面的重要性。结果表明 Pik TE 对微小的底物修饰敏感,