26487-92-3Relevant academic research and scientific papers
Extended stereocontrol in silyl group-transfer cyclizations: Control of four contiguous chiral centers
Klimko,Singleton
, p. 979 - 982 (1994)
The potential for extended stereocontrol in silyl group-transfer cyclizations was explored in model studies which formed four contiguous chiral centers. The diastereofacial selectivity for the reaction of cyclized intermediates was outstanding for both fluoride and SnCl2-trityl chloride mediated reactions. Good simple diastereo-selectivity was observed in reactions initiated by prochiral silyl enolates.
Ring-closing metathesis approaches towards the total synthesis of rhizoxins
Altmann, Karl-Heinz,Liniger, Marc,Neuhaus, Christian M.
supporting information, (2020/10/18)
Efforts are described towards the total synthesis of the bacterial macrolide rhizoxin F, which is a potent tubulin assembly and cancer cell growth inhibitor. A significant amount of work was expanded on the construction of the rhizoxin core macrocycle by ring-closing olefin metathesis (RCM) between C(9) and C(10), either directly or by using relay substrates, but in no case was ringclosure achieved. Macrocycle formation was possible by ring-closing alkyne metathesis (RCAM) at the C(9)/C(10) site. The requisite diyne was obtained from advanced intermediates that had been prepared as part of the synthesis of the RCM substrates. While the direct conversion of the triple bond formed in the ring-closing step into the C(9)-C(10) E double bond of the rhizoxin macrocycle proved to be elusive, the corresponding Z isomer was accessible with high selectivity by reductive decomplexation of the biscobalt hexacarbonyl complex of the triple bond with ethylpiperidinium hypophosphite. Radical-induced double bond isomerization, full elaboration of the C(15) side chain, and directed epoxidation of the C(11)-C(12) double bond completed the total synthesis of rhizoxin F.
Intramolecular Diels-Alder Cycloaddition Approach toward the cis-Fused Δ5,6-Hexahydroisoindol-1-one Core of Cytochalasins
Xu, Jingjing,Lin, Benguo,Jiang, Xiuqing,Jia, Zejun,Wu, Jinlong,Dai, Wei-Min
, p. 830 - 834 (2019/01/26)
Synthesis of the cis-fused Δ5,6-hexahydroisoindol-1-one core of cytochalasins B2-B5, K, Z8, Z9, Z12-Z15, and Z17 has been established starting from an intramolecular D
A Direct Synthesis of Highly Substituted π-Rich Aromatic Heterocycles from Oxetanes
White, Alexander R.,Kozlowski, Ryan A.,Tsai, Shiou-Chuan,Vanderwal, Christopher D.
supporting information, p. 10525 - 10529 (2017/08/22)
The ubiquitous use of π-rich five-membered heterocycles has driven the development of new methods for their synthesis for more than a century. Here, we disclose a general and reliable reaction manifold for the construction of highly substituted heterocycles through a facile Lewis-acid-catalyzed oxetane rearrangement. Notably, this methodology employs a keto-oxetane motif as a 1,4-dicarbonyl surrogate, which can be synthesized using robust alkylation or alkenylation reactions, and thus obviates the need to access 1,4-dicarbonyl compounds via umpoled starting materials. We harnessed this reactivity to generate a broad range of substituted furans and pyrroles, and extended this methodology to produce benzo-fused versions thereof.
Stereoselective olefination of N-sulfonyl imines with stabilized phosphonium ylides for the synthesis of electron-deficient alkenes
Fang, Fan,Li, Yuan,Tian, Shi-Kai
supporting information; experimental part, p. 1084 - 1091 (2011/04/15)
An unprecedented protocol has been developed for thestereoselective synthesis of structurally diverse electron-deficient alkenes in moderate to excellent yields from readily accessible N-sulfonyl imines and stabilized phosphonium ylides. Significantly, the olefination reaction of N-sulfonylimines with nitrile-stabilized phosphonium ylides affords an array of α,β-unsaturated nitriles with high Z selectivity, and the reactions with ester-, amide-, and ketone-stabilized phosphonium ylides afford α,β-unsaturated esters, amides, and ketones with high E selectivity, respectively. Spectroscopic analysis of the reaction mixtures and trapping of the intermediates allow plausible mechanisms to be proposed. Initialimine/ylide addition leads to the formation of betaines that cyclize to form 1,2-azaphosphetanes that subsequently eliminate iminophosphoranes to yield alkenes. For the synthesis of electron-deficient 1,2-disubstituted alkenes, the presence of an electron-withdrawing group in the betaine allows rapid interconversion between its two diastereomers through proton transfer. The Z/E selectivity for alkene synthesis is determined by the different rates at which the two betaine diastereomers form the corresponding 1,2-azaphosphetane diastereomers. In contrast, the Z/E selectivity for the synthesis of electron-deficient trisubstituted alkenes originates from the diastereoselective addition of stabilized phosphonium ylides to N-sulfonyl imines.
Synthesis and Properties of Methano-Bridged Bisdehydro-, -, -annulenones and the Related Compounds
Higuchi, Hiroyuki,Kiyoto, Seiken,Sakon, Chiaki,Hiraiwa, Naoki,Asano, Kaori,et al.
, p. 3519 - 3538 (2007/10/03)
14-Methyl-10,12-bisdehydro-4,9-methano-1H-annulen-1-one, 14-methyl-10,12-bisdehydro-4,9-methano-1H-annulen-1-one, and 16-methyl-12,14-bisdehydro-6,11-methano-1H-annulen-1-one, as well as their methylated and benzannelated derivatives, were synthesized and their tropic properties were studied by NMR and UV spectra under neutral and acidic conditions.The tropicity in these compounds was found to be lower than in their non-bridged monocyclic counterparts.Thus the methano-bridge works to decrease the planarity of the peripherally conjugated system.
Flash Vacuum Pyrolysis of Stabilised Phosphorus Ylides. Part 1. Preparation of Aliphatic and Therminal Alkynes
Aitken, R. Alan,Atherton, J. Ian
, p. 1281 - 1284 (2007/10/02)
Thermal extrusion of Ph3PO from β-oxoalkylidenetriphenylphosphoranes 4 to give the alkynes 5, which under conventional pyrolysis conditions is restricted to cases in which R1 is an electron withdrawing group, has been successfully achieved for R1=H or alkyl by using FVP.The method allows convenient construction of multigram quantities of the alkynes 5 from alkyl halides 1 and allows convenient construction of multigram quantities of the alkynes 5 from alkyl halides 1 and acid chlorides 3 in three steps with good overall yields.Under the conditions used the ylides with R2 = cyclobutyl also undergo less of ethene to provide convenient access to the vinylalkynes 6.
Synthesis and reactions of [1-(trialkylsilyl)alkylidene]triphenylphosphoranes
Bestmann,Bomhard,Dostalek,Pichl,Riemer,Zimmermann
, p. 787 - 792 (2007/10/02)
Alkylidenetriphenylphosphoranes 1 react with trialkyl halosilanes 2 to afford silylated alkylidenephosphoranes 5, which can be converted to acylated alkylidenephosphoranes 8 and 10 by trimethylsilyl carboxylates 6 or carboxylic anhydrides 10. Bis(acylalkylidenephosphoranes) 13-15 are available from 5 and bis(trimethylsilyl) dicarboxylates 12 or cyclic or polymeric anhydrides 16, 17.
Pheromones, 65. - Identification of the Volatile Components of the Mandibular Gland Secretion of the Ant Manica rubida: Structure Elucidation, Synthesis, and Absolute Configuration of Manicone
Bestmann, Hans Juergen,Attygalle, Athula B.,Glasbrenner, Juergen,Riemer, Roland,Vostrowsky, Otto,et al.
, p. 55 - 60 (2007/10/02)
By means of gas chromatography and mass spectrometry, manicone, (4E)-4,6-dimethyl-4-octen-3-one (1), was identified as the main component of the mandibular gland secretion of the ant Manica rubida.In addition the presence of homomanicone (2), bishomomanicone (3), normanicone (7), and a few aliphatic aldehydes and ketones was also evident in the gland.Racemic 1, 2, and 7 and optically active dihydromanicone (4), were synthesized.The (S) configuration of 1 was determined by complexation gas chromatography, on a chiral phase, of 4 as well as of the hydrogenation products of racemic and natural 1.
TOTAL SYNTHESIS OF CARBOMYCIN B AND JOSAMYCIN (LEUCOMYCIN A3)
Tatsuta, Kuniaki,Amemiya, Yoshiya,Maniwa, Shunji,Kinoshita, Mitsuhiro
, p. 2837 - 2840 (2007/10/02)
The stereospecific total synthesis of macrolide antibiotics, carbomycin B and josamycin (leucomycin A3), is described.The key aglycone has been synthesized by coupling two segments of C1-C10 and C11-C16 portions, which are stereospecifically de
