共查询到20条相似文献,搜索用时 15 毫秒
1.
A short, flexible approach to a functionally embellished 7/8/5 fused tricyclic scaffold corresponding to the CDEF segment of Schisanartane nortriterpenoids, from commercially available 1,5-cyclooctadiene, is delineated. 相似文献
2.
C.V. Ramana Mohabul A. Mondal Vedavati G. Puranik Mukund K. Gurjar 《Tetrahedron letters》2006,47(24):4061-4064
The central macrocyclic core of the macrocidins was constructed using RCM as the key reaction. A preliminary investigation dealing with the key reactions, that is, the Dieckmann cyclization and the RCM, revealed that RCM of the β-ketoamide is better than RCM of the corresponding acyltetramic acid. 相似文献
3.
An account of the total synthesis of stephanotic acid methyl ester and celogentin C is presented. The present synthesis features a tandem asymmetric Michael addition/bromination sequence for the synthesis of leucine-tryptophan moiety, and an oxidative coupling reaction to form the tryptophan-imidazole linkage. Moreover, the total synthesis of moroidin had also been studied, and three different synthetic strategies for the construction of the right-hand ring of moroidin were studied. 相似文献
4.
The synthesis of a sugar derived allene and its intramolecular silver mediated etherification followed by ring closing metathesis has been explored for building the tricyclic framework of eunicin. 相似文献
5.
A concise strategy, involving tandem intramolecular Pauson-Khand reactions (IPKRs) on a readily available ene-diyne precursor, to access the dioxa-fenestrane framework is delineated. 相似文献
6.
Suvi T.M. Simila 《Tetrahedron letters》2006,47(17):2933-2936
A concise synthesis of the azatricyclic core structure of FR901483, a potent immunosuppressant, has been accomplished. The key elements of the approach involve a nucleophilic addition to an acyl iminium ion, a ring closing metathesis and a lactone-lactam rearrangement to provide the tricyclic structure. 相似文献
7.
N. Selvakumar P. Kalyan Kumar K. Chandra Shekar Reddy B. Chandra Chary 《Tetrahedron letters》2007,48(11):2021-2024
A variety of allyl acrylates possessing electron-withdrawing groups undergo RCM using the second generation Grubbs’ catalyst in the presence of a Lewis acid resulting in diverse butenolides in high isolated yields. This methodology provides a general route to the natural products of paraconic acids class, exemplified by a total synthesis of (±)-phaseolinic acid. 相似文献
8.
《合成通讯》2013,43(21):3847-3864
Abstract Total synthesis of the nonaromatic cuparenoid sesquiterpenes (±)‐infuscol A and cuprenenol, and (±)‐infuscol B and neocuprenenol isolated from the Japanese liverwort Jungermannia infusca has been accomplished. Two ring‐closing metathesis reaction based strategies have been developed for the generation of the key intermediate of the sequence. 相似文献
9.
Fiona I. McGonagleLindsay Brown Andrew CookeAndrew Sutherland 《Tetrahedron letters》2011,52(18):2330-2332
A microwave-promoted three-step tandem process for the synthesis of bicyclic γ-lactams is developed. In all cases examined this led to significantly faster tandem processes producing the bicyclic γ-lactams more cleanly and reproducibly compared to standard thermal conditions. 相似文献
10.
A concise total synthesis of 11-O-methyldebenzoyltashironin is reported in which oxidative dearomatization-IMDA-RCM triad constitutes the key ring forming steps, while an unorthodox DIBAL-H mediated stereo- and regioselective reductive epoxide openings and implementation of the vinyl bromide-carbonyl equivalency concept were pivotal to the success of this endeavor. 相似文献
11.
Yugandhar Kothapalli Ravi Kumar Puthukanoori Mahesh Ranga Srinivasa Rao Alapati 《Tetrahedron letters》2017,58(40):3831-3833
Crotanecine is the necine base component of a number of pyrrolizidine alkaloids. This necine subunit is an amino triol bearing a primary allylic alcohol characterized by an all-cis relationship of its stereocenters. The synthesis of crotanecine has been accomplished using simple yet versatile ring construction approach using ribose as chiral starting point. 相似文献
12.
Boyapati Veeranjaneyulu Malampati Srilatha Gandolla Chinna Reddy Biswanath Das 《Helvetica chimica acta》2012,95(7):1152-1157
The stereoselective total synthesis of the naturally occurring γ‐lactone derivative botryolide E ( 1 ) was accomplished with acetaldehyde as the starting material (Scheme 2). The asymmetric allyl boration, asymmetric dihydroxylation, chelation‐mediated diastereoselective vinylation, and ring‐closing metathesis reaction are the key steps. The method can conveniently be utilized for the preparation of other related γ‐lactone derivatives. 相似文献
13.
Michela L. Renzulli 《Tetrahedron letters》2004,45(26):5155-5158
The synthesis of bicyclic 3,8-secotaxane diterpenoids, which includes Taxuspine U and X, has been achieved through an approach that involves a ring closing metathesis reaction as key step for the macrocycle formation. 相似文献
14.
关环转换反应是形成碳碳双键的重要反应之一,即双烯化合物在金属碳烯催化下关环得到环烯类化合物。本文概述了关环转换反应所用催化剂体系及其在天然产物合成中的应用,内容涉及到碳环及含氧、含氮杂环天然产物的合成。 相似文献
15.
Synthetic studies directed towards allo-cedrane based, tashironin sibling natural products, involving some deft functional group manipulations on a preformed tetracyclic scaffold, are delineated. 相似文献
16.
The total synthesis of the pyrrolidinone alkaloid rigidiusculamide A is reported starting from L ‐tyrosine, using amidation, ring‐closing metathesis, and dihydroxylation as the key reactions. 相似文献
17.
Christelle Faveau Jean-Pierre Gesson Tobias Mahnke Ulrich Koert 《Tetrahedron letters》2006,47(47):8305-8308
An analogue of the paclitaxel-like antimicrotubule agent laulimalide with a phenyl in place of the dihydropyran has been synthesized. The fragments C1-C14 and C15-C28 were coupled via a stereoselective intermolecular allylboration. Ring closure was achieved using Yamaguchi’s protocol. 相似文献
18.
We describe herein the synthesis of a late-stage intermediate en route to cortistatin A. Key transformations included a Snieckus-like cascade sequence culminating in a 6π-electrocyclization, an alkylative dearomatization, and the stereoselective functionalization of the cortistatin A-ring. While the total synthesis we sought was not accomplished, the work sets the stage for several approaches to the preparation of novel analogs via diverted total synthesis. 相似文献
19.
Mirko Zaja 《Tetrahedron》2004,60(43):9629-9634
An enantioselective synthesis of the quinolizidine alkaloid (−)-lasubine II 1 is reported. Two different pathways to the key intermediate 2 are described. The first case involving a sequence of ring rearrangement metathesis (RRM), simple functional group interconversion operations, followed by a stereoselective cross metathesis (CM) and in the second case a domino ring opening-/ring closing-/cross metathesis step is involved. In both cases, following the metathesis reactions, exclusively the E-isomer was obtained. The final cyclisation towards the quinolizidine skeleton is achieved by an intramolecular Michael reaction. This concept represents the first example of a highly stereoselective RRM-CM combination in the synthesis of a natural product. 相似文献
20.
Divya Agrawal 《Tetrahedron letters》2006,47(43):7615-7618
A concise and enantiospecific route to the 2,6-dioxabicyclo[3.3.0]octan-3-one ring system from commercially available (R)-(+)- and (S)-(−)-glycidols is described. The key features involve ring closing metathesis to construct the 7-substituted-4,5-dehydro-2-oxepanone and its base-catalyzed single-step rearrangement into the 2,6-dioxabicyclo[3.3.0]octan-3-one skeleton. Using this strategy, formal total syntheses of (7R)-cis-Hagen’s gland lactones and (+)- and (−)-trans-kumausynes have been achieved. 相似文献