C–O Ring-Containing Natural Products: Cyanolide A (Krische), Bisabosqual A (Parker), Iso-Eriobrucinol A (Hsung), Trichodermatide A (Hiroya), Batrachotoxin Core (Du Bois)

2017 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Radical Cyclization ◽  
Ethyl Vinyl ◽  
University Of Texas ◽  
Iridium Catalysis ◽  
University Of Wisconsin ◽  
Bisabosqual A ◽  
The University ◽  
Very High

Michael J. Krische at the University of Texas at Austin developed (Angew. Chem. Int. Ed. 2013, 52, 4470) a total synthesis of cyanolide A 7 in only seven steps, a sequence so short it is shown here in its entirety. Diol 1 was subjected to enantioselective cat­alytic bisallylation under iridium catalysis to furnish 2 with very high levels of ste­reocontrol. Cross metathesis using ruthenium catalyst 3 first with ethyl vinyl ketone and then with ethylene resulted in the production of pyran 4. Glycosylation of 4 with phenylthioglycoside 5, stereoselective reduction of the ketone function, and oxidative cleavage of the olefin then furnished the carboxylic acid 6. Finally, dimerization of 6 with 2-methyl-6-nitrobenzoic anhydride (MBNA) yielded cyanolide A. Kathlyn A. Parker at Stony Brook University reported (J. Am. Chem. Soc. 2013, 135, 582) a tandem radical cyclization strategy for the total synthesis of bisabosqual A 11. The key substrate 9 was prepared in three steps from the diester 8. Treatment of 9 with tri-s-butylborane and TTMS in the presence of air induced the tandem 5-exo, 6-exo radical cyclization to produce the complete core 10 of the natural product as a mixture of diastereomers, which could be equilibrated. Some further redox maneu­vers then led to bisabosqual A. Richard P. Hsung at the University of Wisconsin, Madison disclosed (Org. Lett. 2013, 15, 3130) a very brief synthesis of iso-eriobrucinol A and related isomers using a unique cascade sequence. First, phloroglucinol 12 and citral 13 were condensed using piperidine and acetic anhydride. The product of this operation was the tetracy­clic cyclobutane 14, the result of an oxa-[3+3] annulation followed by a stepwise, cat­ionic [2+2] cycloaddition. Treatment of 14 with methyl propiolate in the presence of catalytic indium(III) chloride under microwave irradiation furnished iso-eriobrucinol A, as well as the isomeric natural product iso-eriobrucinol B. A concise approach to trichodermatide A 19 was developed (Angew. Chem. Int. Ed. 2013, 52, 3546) by Kou Hiroya at Musashino University. Aldehyde 16, which was syn­thesized from L-tartaric acid, was condensed with 1,3-cyclohexanedione in the presence of piperidine, resulting in diketone 17.

Organic Functional Group Conversion

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Hong Kong ◽  
Allylic Alcohol ◽  
Primary Alcohols ◽  
National Chemical Laboratory ◽  
Chemical Laboratory ◽  
University Of Texas ◽  
University Of Wisconsin ◽  
Pan American ◽  
Acetate Formation ◽  
The University

Pradeep Kumar of the National Chemical Laboratory, Pune, developed (Tetrahedron Lett. 2010, 51, 744) a new procedure for the conversion of an alcohol 1 to the inverted chloride 3. Michel Couturier of OmegaChem devised (J. Org. Chem. 2010, 75, 3401) a new reagent for the conversion of an alcohol 4 to the inverted fluoride 6. For both reagents, primary alcohols worked as well. Patrick H. Toy of the University of Hong Kong showed (Synlett 2010, 1115) that diethyl-lazodicarboxylate (DEAD) could be used catalytically in the Mitsunobu coupling of 7. Employment of 8 minimized competing acetate formation. In another application of hyper-valent iodine chemistry, Jaume Vilarrasa of the Universitat de Barcelona observed (Tetrahedron Lett. 2010, 51, 1863) that the Dess-Martin reagent effected the smooth elimination of a pyridyl selenide 10. Ken-ichi Fujita and Ryohei Yamaguchi of Kyoto University extended (Org. Lett. 2010, 12, 1336) the “borrowed hydrogen” approach to effect conversion of an alcohol 12 to the sulfonamide 13. Dan Yang, also of the University of Hong Kong, developed (Org. Lett. 2010, 12, 1068, not illustrated) a protocol for the conversion of an allylic alcohol to the allylically rearranged sulfonamide. Shu-Li You of the Shanghai Institute of Organic Chemistry used (Org. Lett. 2010, 12, 800) an Ir catalyst to effect rearrangement of an allylic sulfinate 14 to the sulfone. Base-mediated conjugation then delivered 15. K. Rama Rao of the Indian Institute of Chemical Technology, Hyderabad, devised (Tetrahedron Lett. 2010, 51, 293) a La catalyst for the conversion of an iodoalkene 16 to the alkenyl sulfide 17. Alkenyl selenides could also be prepared. James M. Cook of the University of Wisconsin, Milwaukee, described (Org. Lett. 2010, 12, 464, not illustrated) a procedure for coupling alkenyl iodides and bromides with N-H heterocycles and phenols. Hansjörg Streicher of the University of Sussex showed (Tetrahedron Lett. 2010, 51, 2717) that under free radical conditions, the carboxylic acid derivative 18 could be decarboxylated to the alkenyl iodide 19. Bimal K. Banik of the University of Texas–Pan American found (Synth. Commun. 2010, 40, 1730) that water was an effective solvent for the microwave-mediated addition of a secondary amine 21 to a Michael acceptor 20.

scholarly journals Tom J. Mabry's Natural Products Chemistry Program: 1960–2007

2007 ◽  
Vol 2 (10) ◽  
pp. 1934578X0700201
Author(s):  
Lalita M. Calabria ◽  
Tom J. Mabry
Keyword(s):  
Biological Sciences ◽  
Developmental Biology ◽  
Natural Products ◽  
Faculty Member ◽  
Natural Product ◽  
University Of Texas ◽  
Natural Products Chemistry ◽  
University Of Zurich ◽  
The University ◽  
Natural Product Chemist

This paper presents an overview of Dr. Mabry's accomplishments in his career as a natural product chemist, first at the University of Zürich as a post-doctoral fellow, and from 1962, as a faculty member at the University of Texas at Austin in the Department of Botany until the late 1990s, when the Biological Sciences programs at UT-Austin were completely reorganized. From then until his retirement in 2006, he was a member of the Molecular Cell and Developmental Biology faculty.

Construction of Single Stereocenters

2017 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Asymmetric Hydrogenation ◽  
Bifunctional Catalyst ◽  
Allyl Ether ◽  
University Of Texas ◽  
Iridium Catalysis ◽  
Enantioselective Epoxidation ◽  
Institute Of Technology ◽  
The University ◽  
Academy Of Sciences ◽  
University Of Manchester

Haifeng Du at the Chinese Academy of Sciences reported (J. Am. Chem. Soc. 2013, 135, 6810) the borane-catalyzed asymmetric hydrogenation of imine 1 to 2 using the diene 3 as a chiral ligand for boron. A single-enzyme cascade for the reductive transam­ination of acetophenone 4 with amine 5 to produce enantiopure sec-phenethylamine 6 was developed (Chem. Commun. 2013, 49, 161) by Per Berglund at the KTH Royal Institute of Technology in Sweden. A group at Boehringer Ingelheim in Ridgefield, Connecticut, led by Jonathan T. Reeves, disclosed (J. Am. Chem. Soc. 2013, 135, 5565) a procedure for the addition of DMF anion to N-sulfinyl imine 7 to furnish tert-leucine amide 8 with high diastereoselectivity. The tertiary carbinamine 10 was synthesized (Org. Lett. 2013, 15, 34) via the carbolithiation/rearrangement of vinyl­urea 9 as reported by Jonathan Clayden at the University of Manchester. Gregory C. Fu at Caltech reported (Angew. Chem. Int. Ed. 2013, 52, 2525) that the chiral phosphine 12 catalyzed the enantioselective addition of trifluoroacetamide to allene 11 to produce γ-amino ester 13 in enantioenriched form. Adeline Vallribera at the Autonomous University of Barcelona found (Org. Lett. 2013, 15, 1448) that a euro­pium pybox complex effected the highly enantioselective α-amination of β-ketoester 14 to generate 15 on the way to the Parkinson’s disease co-drug L-carbidopa. Hisashi Yamamoto at the University of Chicago and Chubu University reported (J. Am. Chem. Soc. 2013, 135, 3411) that a halfnium(IV) complex of the bishydroxamic acid 17 catalyzed the enantioselective epoxidation of the tertiary homoallylic alcohol 16 to 18. The rearrangement of the allylic carbonate 19 to produce allyl ether 21 with high ee under iridium catalysis in the presence of ligand 20 was disclosed (Org. Lett. 2013, 15, 512) by Hyunsoo Han at the University of Texas, San Antonio. The asymmetric vinylogous aldol reaction of 3-methyl-2-cyclohexen-1-one 22 and α-keto ester 23 to furnish tertiary carbinol 25 using the bifunctional catalyst 24 was developed (Org. Lett. 2013, 15, 220) by Paolo Melchiorre at ICREA and ICIQ in Spain.

C–O Containing Natural Products

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Biological Activities ◽  
Max Planck ◽  
Penicillium Species ◽  
Antimitotic Agent ◽  
Berkelic Acid ◽  
Metal Catalyzed ◽  
The University

It is thought that the pseudopterane class of diterpenoid natural products, of which 11-gorgiacerol is a member, arises biosynthetically by a photo-ring contraction of the related furanocembranes. Johann Mulzer at the University of Vienna has applied (Org. Lett. 2012, 14, 2834) this logic to realize the total synthesis of 11-gorgiacerol. Ringclosing metathesis of the butenolide 1 using the Grubbs second generation catalyst produced the tricycle 2. When irradiated, 2 undergoes a 1,3-rearrangement to furnish the natural product in good yield. Whether this rearrangement is concerted, or occurs stepwise via a diradical intermediate, is not known. Although ring-closing metathesis has become a reliable method for macrocycle construction, its use here to set what then becomes an extracyclic olefin is notable. Berkelic acid is produced by an extremophile bacterium penicillium species that lives in the toxic waters of an abandoned copper mine, and this natural product has been found to possess some very intriguing biological activities. Not surprisingly, berkelic acid has attracted significant attention from synthetic chemists, including Francisco J. Fañanás of Universidad de Oviedo in Spain, who has developed (Angew. Chem. Int. Ed. 2012, 51, 4930) a scalable, protecting-group free total synthesis. The key step in this route is the remarkable silver(I)-catalyzed coupling of alkyne 3 and aldehyde 4 to produce, after hydrogenation, the structural core 5 of (–)-berkelic acid on a gram scale. Some tools from the field of organocatalysis have been brought to bear (Angew. Chem. Int. Ed. 2012, 51, 5735) on a new total synthesis of the macrolide (+)-dactylolide by Hyoungsu Kim of Ajou University in Korea and Jiyong Hong of Duke University. The bridging tetrahydropyranyl ring is fashioned by way of an intramolecular 1,6-oxa conjugate addition of dienal 6 to produce 8 under catalysis by the secondary amine 7. Following some synthetic manipulations, the macrocyclic ring 12 is subsequently forged by an NHC-catalyzed oxidative macrolactonization using the carbene catalyst 10 and diphenoquinone 11 as the oxidant. A new approach to the nanomolar antimitotic agent spirastrellolide F methyl ester has been reported (Angew. Chem. Int. Ed. 2012, 51, 8739) by Alois Fürstner of the Max-Planck-Institut, Mülheim. Two elegant metal-catalyzed processes form the key basis of this strategy.

Total Synthesis of C–O Natural Products

2017 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Total Synthesis ◽  
Claisen Rearrangement ◽  
Innovative Strategy ◽  
University Of Wisconsin ◽  
Enyne Cyclization ◽  
Free Hydroxyl ◽  
Tokyo Institute ◽  
Institute Of Technology ◽  
Oxidopyrylium Cycloaddition ◽  
The University

Weiping Tang at the University of Wisconsin, Madison reported (J. Am. Chem. Soc. 2013, 135, 12434) the total synthesis of the tropone-containing norditerpenes hain­anolidol 6 and harringtonolide 7 by making use of a strategic [5+2] oxidopyrylium cycloaddition. First, the known ketone 1 was converted through a number of steps to cycloaddition precursor 2. Treatment with DBU then effected the key cycloaddition to furnish the complex polycyclic compound 3. Additional manipulations revealed struc­ture 4 with the lactone ring in place. The tropone ring of the natural structures was con­structed by reaction of the cycloheptadiene moiety of 4 with singlet oxygen followed by Kornblum- DeLaMare rearrangement with DBU to afford ketone 5. Double elimination using TsOH then produced hainanolidol 6. The free hydroxyl of 6 was engaged in a C–H-functionalizing cyclization using Pd(OAc)₄ to yield harringtonolide 7 as well. Hanfeng Ding at Zhejiang University developed (Angew. Chem. Int. Ed. 2013, 52, 13256) a concise route to indoxamycin F 12 (as well as the related indoxamy­cins A and C). The complex intermediate 9 was accessed in only four steps from the bicyclic ketone 8, which in turn was prepared by a route involving an Ireland–Claisen rearrangement and a reductive 1,6-enyne cyclization (not shown). An impressive oxa-conjugate addition/methylenation reaction to produce 11 was accomplished by treat­ment of 9 with Grignard 10 followed by Eschenmoser’s salt. Some final decorative work then led to indoxamycin F 12. The strained polycyclophane natural product cavicularin 18 was synthesized in enantioenriched form by an innovative strategy reported (Angew. Chem. Int. Ed. 2013, 52, 10472) by Keisuke Suzuki at the Tokyo Institute of Technology.

Total Synthesis of (+)-Mintlactone and (–)-Isomintlactone via SmI2-Induced Radical Cyclization

Synlett ◽  
2017 ◽  
Vol 28 (13) ◽  
pp. 1660-1662 ◽  
Author(s):  
Dian He ◽  
Zhen Wang ◽  
Xiaodong Wang ◽  
Huihong Wang ◽  
Xia Wu ◽  
...  
Keyword(s):  
Transition State ◽  
Total Synthesis ◽  
Natural Product ◽  
Radical Cyclization ◽  
One Step

A divergent strategy has been used to concisely and efficiently complete the synthesis of (+)-mintlactone and (–)-isomintlactone via SmI2-induced intramolecular radical cyclization, two rings and a stereocenter were constructed in one step. In the synthesis, the stereochemistry of the final natural product is set relative to the stereocenter of (–)-citronellol and favored coordination transition state of samarium atom with substrate.

Construction of Single Stereocenters

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Medical Center ◽  
Columbia University ◽  
Santa Barbara ◽  
Electrophilic Amination ◽  
Ene Reaction ◽  
University Of Texas ◽  
University Of Wisconsin ◽  
Nucleophilic Displacement ◽  
Institute Of Technology ◽  
The University

James L. Leighton at Columbia University reported (Nature 2012, 487, 86) that the commercially available allylsilane 2 allylated acetoacetone (1) to furnish the enantioenriched tertiary carbinol 3. Alexander T. Radosevich demonstrated (Angew. Chem. Int. Ed. 2012, 51, 10605) that diazaphospholidine 5 induced the formal reductive insertion of 3,5-dinitrobenzoic acid to α-ketoester 4 to generate adduct 6 enantioselectively. Tehshik P. Yoon at the University of Wisconsin at Madison found (J. Am Chem. Soc. 2012, 134, 12370) that aminoalcohol derivative 9 could be prepared via an asymmetric iron-catalyzed oxyamination of diene 7 using oxaziridine 8. A procedure for the desymmetrization of 1,3-difluoropropanol 10 by nucleophilic displacement of an unactivated aliphatic fluoride to generate 11 was reported (Angew. Chem. Int. Ed. 2012, 51, 12275) by Günter Haufe at the University of Münster and Norio Shibata at the Nagoya Institute of Technology. An innovative procedure for the amination of unactivated olefins involving an ene reaction/[ 2,3]-rearrangement sequence (e.g., 12 to 13) was developed (J. Am. Chem. Soc. 2012, 134, 18495) by Uttam K. Tambar at the University of Texas Southwestern Medical Center. James P. Morken at Boston College demonstrated the stereospecific amination of borane 14 with methoxylamine to produce 15. The conversion of β-ketoester 16 to 18 by amination with 17 under oxidative conditions was reported (J. Am. Chem. Soc. 2012, 134, 18948) by Javier Read de Alaniz at the University of California at Santa Barbara. The electrophilic amination of silyl ketene acetal 19 with a functionalized hydroxylamine reagent to produce 20 was disclosed (Angew. Chem. Int. Ed. 2012, 51, 11827) by Koji Hirano and Masahiro Miura at Osaka University. Erick M. Carreira at ETH Zürich developed (Angew. Chem. Int. Ed. 2012, 51, 8652) the enantioconvergent thioetherification of alcohol 21 to produce 23 with high branched to linear selectivity and ee. The asymmetric conjugate addition of 2-aminothiophenol 25 to 24 catalyzed by mesitylcopper in the presence of ligand 26 was developed (Angew. Chem. Int. Ed. 2012, 51, 8551) by Naoya Kumagai and Masakatsu Shibasaki at the Institute of Microbial Chemistry in Tokyo. The enantioselective conversion of aldehyde 28 to α-fluoride 30 under catalysis by NHC 29 was developed (Angew. Chem. Int. Ed. 2012, 51, 10359) by Zhenyang Lin and Jianwei Sun at the Hong Kong University of Science and Technology.

scholarly journals Total Synthesis of Oxepin and Dihydrooxepin Containing Natural Products

Synthesis ◽  
2021 ◽  
Author(s):  
Thomas Magauer ◽  
Kevin Rafael Sokol
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Radical Cyclization ◽  
Sigmatropic Rearrangement ◽  
Natural Product Synthesis ◽  
Synthetic Methods ◽  
Acid Catalyzed ◽  
Metal Catalyzed ◽  
Key Steps

AbstractThe construction of oxepin and dihydrooxepin containing natural products represents a challenging task in total synthesis. In the last decades, a variety of synthetic methods have been reported for the installation of these structural motifs. Herein, we provide an overview of synthetic methods and strategies to construct these motifs in the context of natural product synthesis and highlight the key steps of each example.1 Introduction2 Oxepin Natural Products3 Dihydrooxepin Natural Products3 Brønsted or Lewis acid Catalyzed Cyclization3.2 Radical Cyclization3.3 Substitution and Addition Cyclization3.4 Sigmatropic Rearrangement3.5 Oxidative Methods3.6 Transition Metal Catalyzed Cyclization4 Summary

scholarly journals The Joe Meyer Estate #1 Site (41SM73) on Saline Creek in the Upper Neches River Basin in East Texas

2015 ◽  
Author(s):  
Timothy K. Perttula
Keyword(s):  
River Basin ◽  
17Th Century ◽  
East Texas ◽  
Small Surface ◽  
University Of Texas ◽  
Southern Methodist University ◽  
The University ◽  
Neches River ◽  
Very High

The Joe Meyer Estate #1 site (41SM73) is an ancestral Caddo settlement and cemetery on an upland landform west of Saline Creek, a southern-flowing tributary of the Neches River in the upper Neches River basin. In the spring of 1957 members of the East Texas Archeological Society (ETAS), including John Mulligan, Sam Whiteside, Derrell Sanders, and Jowell Proctor, had located the site and commenced excavations. The site had substantial midden deposits as well as Caddo burial features. W. A. Davis and E. Mott Davis of The University of Texas visited the site in April 1957, took notes on the burial features and associated funerary offerings, and obtained a surface collection of artifacts. The summer of 1957, LeRoy Johnson, Jr. visited the site and obtained a surface collection as part of a broader survey of Blackburn Crossing Reservoir (now Lake Palestine) on the Neches River. In December 1957, E. Mott Davis visited the site again, at which time ETAS members had excavated two test pits (A and B) in the midden deposits. In June 1969 George Kegley and Dan Witter returned to the site, and made a small surface collection. They also noted that at least 25 Caddo burials (some, if not all, of apparent post-A.D. 1400 age based on the finding of Poynor Engraved vessels) had been excavated in 1966-1967 in another cemetery at the site; one of the main excavators of this cemetery was William “Red” McFarland of Whitehouse, Texas, a well known East Texas digger; this same cemetery may have also been explored by Buddy Jones and ETAS members some years before, where two burials were excavated. Finally, in August 1969 and March 1970, archaeologists from Southern Methodist University (SMU) returned to the Joe Meyer Estate #1 site as part of a more intensive survey of proposed Lake Palestine. A large assemblage of ceramic sherds (n=596) was collected from the surface of the site as part of this survey. About 86 percent of the decorated sherds in this assemblage were from brushed jars, suggesting the sherds were collected from a Late Caddo occupation area, probably an occupation dating to the 17th century given the very high proportion of brushed sherds in the decorated sherd assemblage. The Joe Meyer Estate #1 site was not one of the sites selected for excavation by SMU before construction of the reservoir, likely because the site was not to be inundated by the reservoir flood pool. There have been no professional archaeological investigations at the site since 1970.

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