- Synthetic Studies of the Rubellin Natural Products: Development of a Stereoselective Strategy and Total Synthesis of (+)-Rubellin C
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This manuscript describes our studies of the class of natural products known as the rubellins, culminating in the total synthesis of (+)-rubellin C. These anthraquinone-based natural products contain a variety of stereochemical and architectural motifs, including a 6-5-6-fused ring system, 5 stereogenic centers, and a central quaternary center. Herein, we report our development of a strategy to target the stereochemically dense core and anthraquinone nucleus, including approaches such as a bifunctional allylboron and vinyl triflate reagent, an anthraquinone benzylic metalation strategy, and a late-stage anthraquinone introduction strategy. Our studies culminate in a successful route to highly functionalized anthraquinone-based natural product scaffolds and a stereoselective total synthesis of (+)-rubellin C. These strategies and outcomes will aid in synthetic planning toward anthraquinone-based natural products of high interest.
- Gartman, Jackson A.,Tambar, Uttam K.
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p. 11237 - 11262
(2021/08/16)
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- Total Synthesis of (+)-Rubellin C
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The rubellins are a family of stereochemically complex anthraquinoid heterodimers containing an unprecedented chemical scaffold. Although the rubellins have been known for over three decades, no total synthesis has been achieved since their discovery. The
- Gartman, Jackson A.,Tambar, Uttam K.
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supporting information
p. 9145 - 9150
(2020/08/24)
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- Asymmetric synthesis of novel spirocycles via a chiral phosphoric acid catalyzed desymmetrization
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A straightforward method for the asymmetric preparation of novel lactone and lactam spirocycles is described. An initial desymmetrization via a chiral Br?nsted acid yields enantioenriched lactones which readily undergo a second cyclization to give the des
- Kelley, Amber M.,Minerali, Eni,Wilent, Jennifer E.,Chambers, Nicholas J.,Stingley, Kyla J.,Wilson, G. Tyler,Petersen, Kimberly S.
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supporting information
p. 1262 - 1264
(2019/04/10)
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- An efficient and chemoselective deprotection of aryl tert-butyldimethylsilyl (TBDMS) ethers by NaCN
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Phenolic tert-butyldimethylsilyl (TBDMS) ethers can be deprotected to yield phenols in excellent yield using sodium cyanide (NaCN) as catalyst in ethanol. The deprotectation of various phenolic TBDMS ethers were found to be very convenient, fast, high yielding and chemoselective.
- Qiao, Xue-Jun,Hou, Xiao,Fang, Wu-Hong,Bao, Xue-Fei,Chen, Guo-Liang
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p. 899 - 904
(2016/05/19)
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- 7-MEMBERED FUSED HETEROCYCLES AND METHODS OF THEIR SYNTHESIS
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Disclosed are a new method for synthesizing 7-membered fused heterocycles and compounds synthesized by the new method. The method involves a dual activation strategy using an N-heterocyclic carbene catalyst as a first Lewis base and another second Lewis b
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Paragraph 0101; 0102; 0103
(2015/03/16)
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- A dual Lewis base activation strategy for enantioselective carbene-catalyzed annulations
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A dual activation strategy integrating N-heterocyclic carbene (NHC) catalysis and a second Lewis base has been developed. NHC-bound homoenolate equivalents derived from α,β-unsaturated aldehydes combine with transient reactive o-quinone methides in an ena
- Izquierdo, Javier,Orue, Ane,Scheidt, Karl A.
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supporting information
p. 10634 - 10637
(2013/08/23)
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- Click-connected ligand scaffolds: macrocyclic chelates for asymmetric hydrogenation
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Click chemistry is used to construct ligand scaffolds for a series of chiral diphosphites. Enantioselectivity as high as 97% ee is obtained using these click ligands in rhodium-catalyzed asymmetric hydrogenation. Control experiments and spectroscopic data suggest that a 16-membered P,P-macrocyclic Rh(1) chelate is formed.
- Qing, Zhang,Takacs, James M.
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p. 545 - 548
(2008/09/17)
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- TRICYCLIC GUANIDINE DERIVATIVES AS SODIUM-PROTON EXCHANGE INHIBITORS
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Guanidine derivatives having a condensed tricyclic ring of formula 1: are disclosed, wherein U is C(O), CRaRb, O, NRa or S(O)m V is CRaRb or NRa; W is S(O)m ; wherein Ra is H, alkyl, cycloalkyl, alkenyl or aralkyl; Rb is H, alkyl, OH, ORa or OCORa, and m is the integer 0, 1 or 2; R1, R2, R3, R4, R5, R6, R7 and R8 are as defined herein with the proviso that at least one of R1, R2, R3, R4, R5, R6, R7 or R8 is guanidino or guanidino carbonyl. These derivatives are sodium-proton exchange inhibitors and are useful as medicaments for the treatment of, for example, organ disorders associated with ischemia and reperfusion, cardiac arrhythmia, cardiac hypertrophy, hypertension, cell proliferative disorders and diabetes.
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Page/Page column 89
(2010/11/30)
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- MORPHOLINE DERIVATIVES AS NOREPINEPHRINE REUPTAKE INHIBITORS
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Compounds of the general formula (I) are inhibitors of the reuptake of norepinephrine. As such, they may be useful for the treatment of disorders of the central and/or peripheral nervous system.
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Page/Page column 43-44
(2008/06/13)
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- An Effective Approach for the Silylation of Hydroxyl Compounds in Room Temperature Ionic Liquids
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The room temperature ionic liquid (RTIL) 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6) is used as a "green" recyclable alternative to conventional solvents for the silylation of a series of hydroxyl compounds (alcohols and phenols
- Xu, Zhen-Yuan,Xu, Dan-Qian,Liu, Bao-You,Luo, Shu-Ping
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p. 4143 - 4149
(2007/10/03)
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- A Convenient Method for Protection and Deprotection of Alcohols and Phenols as Alkylsilyl Ethers Catalyzed by Iodine under Microwave Irradiation
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Irradiation of alcohols or phenols with tert-butyldimethylsilyl chloride (TBDMSCl) or trimethylsilyl chloride (TMSCl) in presence of catalytic amount (20 mol%) of iodine in a microwave oven for 2 min gives the corresponding silyl ethers in excellent yield. Iodine in methanol deprotects the silyl ether into its parent alcohol or phenol under similar reaction conditions.
- Saxena, Ira,Deka, Nabajyoti,Sarma, Jadab C.,Tsuboi, Sadao
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p. 4185 - 4191
(2007/10/03)
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- PROCESS FOR PREPARATION OF CHEMICAL COMPOUNDS
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The present invention relates to a process for the preparation of certain chemical compounds. In particular, the present invention relates to a method for the preparation of compounds that have been shown to activate human peroxisome proliferator activate
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Page/Page column 37
(2010/02/07)
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- Catalyst for aromatic C—O, C—N, and C—C bond formation
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The present invention is directed to a transition metal catalyst, comprising a Group 8 metal and a ligand having the structure wherein R, R′ and R″ are organic groups having 1-15 carbon atoms, n=1-5, and m=0-4. The present invention is also directed to a method of forming a compound having an aromatic or vinylic carbon-oxygen, carbon-nitrogen, or carbon-carbon bond using the above catalyst. The catalyst and the method of using the catalyst are advantageous in preparation of compounds under mild conditions of approximately room temperature and pressure.
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- Air stable, sterically hindered ferrocenyl dialkylphosphines for palladium-catalyzed C-C, C-N, and C-O bond-forming cross-couplings
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Pentaphenylferrocenyl di-tert-butylphosphine has been prepared in high yield from a two-step synthetic procedure, and the scope of various cross-coupling processes catalyzed by complexes bearing this ligand has been investigated. This ligand creates a remarkably general palladium catalyst for aryl halide amination and for Suzuki coupling. Turnovers of roughly 1000 were observed for aminations with unactivated aryl bromides or chlorides. In addition, complexes of this ligand catalyzed the formation of selected aryl ethers under mild conditions. The reactions encompassed electron-rich and electron-poor aryl bromides and chlorides. In the presence of catalysts containing this ligand, these aryl halides coupled with acyclic or cyclic secondary alkyl- and arylamines, with primary alkyl- and arylamines, and with aryl- and primary alkylboronic acids. These last couplings provide the first general procedure for reaction of terminal alkylboronic acids with aryl halides without toxic or expensive bases. The ligand not only generates highly active palladium catalysts, but it is air stable in solution and in the solid state. Palladium(0) complexes of this ligand are also air stable as a solid and react only slowly with oxygen in solution.
- Kataoka, Noriyasu,Shelby, Quinetta,Stambuli, James P.,Hartwig, John F.
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p. 5553 - 5566
(2007/10/03)
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- A new preparation of 2,5-dihydro-1-benzoxepins using Mitsunobu cyclization, and the synthesis of natural radulanins
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Mitsunobu cyclization of o-[4-hydroxy-3-methyl-2(Z)-butenyl]phenol 2a effected selective seven-membered cyclization to give 3-methyl-2,5-dihydro-1- benoxepin 1a. Using this procedure, natural radulanin A and radulanin A methyl ether were synthesized effec
- Yamaguchi, Seiji,Furihata, Katsunori,Miyazawa, Masahiro,Yokoyama, Hajime,Hirai, Yoshiro
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p. 4787 - 4790
(2007/10/03)
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- Facile methods for the direct conversions of aryl acetates into the corresponding methoxymethyl ethers or silyl ethers
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Direct conversion of aryl acetates into aryl methoxymethyl ethers or aryl trialkylsilyl ethers was readily accomplished by treatment with methoxymethyl bromide or trialkylsilyl trifluoromethanesulfonate, respectively, in the presence of sodium methoxide.
- Oriyama, Takeshi,Noda, Kojiro,Sugawara, Satomi
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p. 2217 - 2223
(2007/10/03)
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- Polymer-supported reactions in organic synthesis: Part 1 - Protection and deprotection of phenols using anion exchange resin.
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Phenoxide ions supported on Amberlite IRA-400 (chloride form) are protected as t-butyl(dimethyl)silyl (TBDMS) ethers in good to excellent yields and subsequently deprotected by fluoride ions supported on Amberlite IRA-400 (chloride form).
- Bandgar, B. P.,Unde, S. D.,Unde, D. S.,Kulkarni, V. H.,Patil, S. V.
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p. 782 - 784
(2007/10/03)
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