共查询到20条相似文献,搜索用时 15 毫秒
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近年来,分子内环加成反应已广泛用于甾体化合物全合成,其主要一步是由取代的苯并环丁烯热裂而成的5,6-二亚甲基-1,3-环己二烯发生区域专一和立体选择性的环加成反应,构成甾体骨架。现在用此法已合成了一系列消旋和光学活性的甾体化合物。 相似文献
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Laurence Miesch Dr. Tania Welsch Vincent Rietsch Michel Miesch Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(17):4394-4401
Selecting the ring : tert‐Butyldimethylsilyltriflate (TBSOTf)/NEt3 treatment of alkynyl esters tethered to bicycloalkanones leads to the formation of tricyclic allenoates with total diasteroselectivity at the ring junction. An intramolecular alkynylogous Mukaiyama aldol reaction promoted by a TBSOTf/NEt3 dual activation is involved. This novel methodology was illustrated by a formal total synthesis of (±)‐hamigeran B.
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K. C. Nicolaou Scott A. Snyder Tamsyn Montagnon Georgios Vassilikogiannakis 《Angewandte Chemie (International ed. in English)》2002,41(10):1668-1698
The Diels–Alder reaction has both enabled and shaped the art and science of total synthesis over the last few decades to an extent which, arguably, has yet to be eclipsed by any other transformation in the current synthetic repertoire. With myriad applications of this magnificent pericyclic reaction, often as a crucial element in elegant and programmed cascade sequences facilitating complex molecule construction, the Diels–Alder cycloaddition has afforded numerous and unparalleled solutions to a diverse range of synthetic puzzles provided by nature in the form of natural products. In celebration of the 100th anniversary of Alder's birth, selected examples of the awesome power of the reaction he helped to discover are discussed in this review in the context of total synthesis to illustrate its overall versatility and underscore its vast potential which has yet to be fully realized. 相似文献
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Lu Pan Chang-Wu Zheng Guo-Sheng Fang Hao-Ran Hong Jun Liu Long-Hui Yu Prof. Gang Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(25):6306-6310
An asymmetric total synthesis of vincadifformine is described. The limited tactics with chiral cation-directed catalysis in total synthesis inspired the development of our strategy for accessing this alkaloid in enantionrich form. The route features a thiourea–phosphonium salt catalyzed Mannich-type reaction, a phosphine-promoted aza-Morita–Baylis–Hillman reaction and a trifluoroacetic acid promoted deprotection/amidation cascade process. 相似文献
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Dr. Shu Xu Daisuke Unabara Prof. Dr. Daisuke Uemura Prof. Dr. Hirokazu Arimoto 《化学:亚洲杂志》2014,9(1):367-375
The enantioselective total synthesis of the bioactive marine natural products pinnaic acid and halichlorine is reported in detail. Our total synthesis features the construction of the five‐membered ring and C9 and C13 stereogenic centers through a palladium‐catalyzed trimethylenemethane [3+2] cyclization; the installation of the nitrogen atom through a regioselective Beckmann rearrangement of a poorly reactive ketone; the stereoselective cyclization of the spiro ring through a four‐step, one‐pot hydrogenation–cyclization; and efficient connection of the sterically hindered lower chain through a reduced‐pressure cross olefin metathesis reaction. 相似文献
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Yonglei Que Hao Shao Haibing He Shuanhu Gao 《Angewandte Chemie (International ed. in English)》2020,59(19):7444-7449
The asymmetric total synthesis of farnesin, a rearranged ent‐kaurenoid, was achieved through a convergent approach involving photo‐Nazarov and intramolecular aldol cyclizations to build the syn‐syn‐syn hydrofluorenol ABC ring system and bicyclo[3.2.1]octane CD ring system in the first application of a UV‐light‐induced excited‐state Nazarov cyclization of a non‐aromatic dicyclic divinyl ketone in a total synthesis. Unlike the conventional acid‐promoted ground‐state Nazarov reaction, the excited‐state Nazarov reaction enables stereospecific formation of the highly strained syn‐syn‐syn‐fused hydrofluorenone scaffold through a disrotatory cyclization. 相似文献
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Dr. You‐Ming Huang Dr. Yang Liu Dr. Chang‐Wu Zheng Qiao‐Wen Jin Lu Pan Ren‐Ming Pan Jun Liu Prof. Dr. Gang Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(51):18339-18342
The total synthesis of gelsedilam, which features a highly diastereoselective thiol conjugate addition–intramolecular aldol reaction to install the strained and caged [3.2.2] bridged ring system and highly efficient NiCl2/NaBH4‐mediated four‐step transformation in one‐pot to construct its five‐membered lactam ring is reported. The synthesis requires only 18 linear steps from the known compounds, providing useful strategies for the construction of the intricate ring system in the synthesis of related gelsedine‐type alkaloids. 相似文献
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An asymmetric total synthesis of (+)-7-epi-tarchonanthuslactone was achieved from commercially available methyl (R)-3-hydroxybutyrate. The key step employed a diastereoselective chelation-controlled Mukaiyama aldol reaction to construct the chiral hydroxyl group at the C-5 position. 相似文献
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Nataliia V. Shymanska Il Hwan An Prof. Joshua G. Pierce 《Angewandte Chemie (International ed. in English)》2014,53(21):5401-5404
A five‐step total synthesis of the marine natural product synoxazolidinone A was achieved through a diastereoselective imine acylation/cyclization cascade. Synoxazolidinone B and a series of analogues were also prepared to explore the potential of these 4‐oxazolidinone natural products as antimicrobial agents. These studies confirmed the importance of the chlorine substituent for antimicrobial activity and revealed simplified dichloro derivatives that are equally potent against several bacterial strains. 相似文献
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Jerry Isaacson Yoshihisa Kobayashi Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(10):1845-1848
(?)‐Dysibetaine has been synthesized in 11 steps from readily available L ‐malic acid (see scheme). The key step is a unique Ugi 4‐center‐3‐component cyclization reaction, where an ester group acts as the carboxylic acid component. The use of 1,1,1,3,3,3‐hexamethyldisilazane as an ammonia equivalent and a specially designed isocyanide leads to an expeditious synthesis.
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Bhaswati Ghosh Yen‐Hsun Lai Yu‐Yin Shih Dr. Tapan Kumar Pradhan Prof. Dr. Chun‐Hung Lin Prof. Dr. Kwok‐Kong Tony Mong 《化学:亚洲杂志》2013,8(12):3191-3199
The total synthesis of a glycoglycerolipid isolate of Meiothermus taiwanensis and its truncated structural analogues is reported. Our synthesis employed DMF‐modulated and low‐concentration glycosylation reactions for the construction of α‐ and β‐glycosidic bonds in the absence of participating protecting groups. Further simplification of the synthesis was achieved by employing a low‐concentration one‐pot glycosylation procedure. Preliminary immunological studies showed that one of the truncated structural analogues suppressed the cytokine production of THP‐1 monocytes. 相似文献