C–N Ring Construction: The Harrity Synthesis of Quinolizidine (–)-217A

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Phase Transfer ◽  
Iron Catalyst ◽  
Free Acid ◽  
Oxidative Cyclization ◽  
Colorado State University ◽  
University Of Tennessee ◽  
National University ◽  
Chiral Bronsted Acid ◽  
Enantioselective Alkylation ◽  
Seoul National University

David M. Jenkins of the University of Tennessee devised (J. Am. Chem. Soc. 2011, 133, 19342) an iron catalyst for the aziridination of an alkene 1 with an aryl azide 2. Yoshiji Takemoto of Kyoto University cyclized (Org. Lett. 2011, 13, 6374) the prochiral oxime derivative 4 to the azirine 5 in high ee. Organometallics added to 5 syn to the pendant ester. Hyeung-geun Park of Seoul National University used (Adv. Synth. Catal. 2011, 353, 3313) a chiral phase transfer catalyst to effect the enantioselective alkylation of 6 to 7. Yian Shi of Colorado State University showed (Org. Lett. 2011, 13, 6350) that a chiral Brønsted acid mediated the enantioselective cyclization of 8 to 9. Mattie S.M. Timmer of Victoria University of Wellington and Bridget L. Stocker of Malaghan Institute of Medical Research effected (J. Org. Chem. 2011, 76, 9611) the oxidative cyclization of 10 to 11. They also showed (Tetrahedron Lett. 2011, 52, 4803, not illustrated) that the same cyclization worked well to construct piperidine derivatives. Jose L. Vicario of the Universidad del País Vasco extended (Adv. Synth. Catal. 2011, 353, 3307) organocatalysis to the condensation of 12 with 13 to give the pyrrolidine 14. Jinxing Ye of the East China University of Science and Technology used (Adv. Synth. Catal. 2011, 353, 343) the same Hayashi catalyst to condense 15 with 16 to give 17. André B. Charette of the Université de Montreal expanded (Org. Lett. 2011, 13, 3830) 18, prepared by Petasis-Mannich coupling followed by ring-closing metathesis, to the piperidine 20. Marco Bella of the “Sapienza” University of Roma effected (Org. Lett. 2011, 13, 4546) enantioselective addition of 22 to the prochiral 21 to give 23. Ying-Chun Chen of Sichuan University and Chun-An Fan of Lanzhou University cyclized (Adv. Synth. Catal. 2011, 353, 2721) 24 to 25 in high ee. Andreas Schmid of TU Dortmund showed (Adv. Synth. Catal. 2011, 353, 2501) that ω-laurolactam hydrolases could be used to cyclize the ester 26, but not the free acid, to the macrolactam 27.

Construction of Alkylated Stereogenic Centers

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Phase Transfer ◽  
Conjugate Addition ◽  
Enantioselective Hydrogenation ◽  
Boronic Acids ◽  
National University ◽  
Cu Catalyst ◽  
Institute Of Technology ◽  
Enantioselective Alkylation ◽  
Seoul National University ◽  
The University

Andreas Pfaltz of the University of Basel and Keisuke Suzuki of the Tokyo Institute of Technology showed (Angew. Chem. Int. Ed. 2010, 49, 881) that the iodohydrin of 1 did not interfere with the enantioselective hydrogenation. J. R. Falck of UT Southwestern developed (J. Am. Chem. Soc. 2010, 132, 2424) a procedure for coupling arene boronic acids with a cyano triflate 3, readily available in high ee from the corresponding aldehyde. Anita R. Maguire of University College Cork devised (J. Am. Chem. Soc. 2010, 132, 1184) a Cu catalyst for the enantioselective C-H insertion cyclization of 5 to 6. Jin-Quan Yu of Scripps/La Jolla established (J. Am. Chem. Soc. 2010, 132, 460) a complementary enantioselective C-H functionalization protocol, converting the prochiral 7 into 8 in high ee. Xumu Zhang of Rutgers University effected (Angew. Chem. Int. Ed. 2010, 49, 4047) enantioselective branching hydroformylation of 9 to give 10. T. V. RajanBabu of Ohio State University established (J. Am. Chem. Soc. 2010, 132, 3295) the enantioselective hydrovinylation of a diene 11 to the diene 12. Gregory C. Fu extended (J. Am. Chem. Soc. 2010, 132, 1264, 5010) Ni-mediated cross-coupling, both with alkenyl and aryl nucleophiles, to the racemic bromoketone 13. Hyeung-geun Park and Sang-sup Jew of Seoul National University used (Organic Lett. 2010, 12 , 2826) their asymmetric phase transfer protocol to effect the enantioselective alkylation of the amide 15. Kyung Woon Jung of the University of Southern California showed (J. Org. Chem. 2010, 75, 95) that the oxidative Pd-mediated Heck coupling of arene boronic acids to 17 could be effected in high ee. Nicolai Cramer of ETH Zurich observed (J. Am. Chem. Soc. 2010, 132, 5340) high enantioinduction in the cleavage of the prochiral cyclobutanol 19. Alexandre Alexakis of the University of Geneva achieved (Organic Lett. 2010, 12, 1988) the long-sought goal of efficient enantioselective conjugate addition of a Grignard reagent to an unsaturated aldehyde 21. Professor Alexakis also established (Organic Lett. 2010, 12, 2770) conditions for enantioselective conjugate addition to a nitrodiene 23. This procedure worked equally well for β-alkynyl nitroalkenes.

Functional Group Interconversion

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Carboxylic Acid ◽  
High Yield ◽  
Staudinger Ligation ◽  
University Of Alberta ◽  
University Of Tennessee ◽  
University Of British Columbia ◽  
National University ◽  
Seoul National University ◽  
Oxidative Amidation ◽  
The University

Glenn M. Samm is at the University of British Columbia reported (Angew. Chem. Int. Ed. 2012, 51, 10804) the photofluorodecarboxylation of aryloxyacids such as 1 using Selectfluor 2. Jean-François Paquin at the Université Laval found (Org. Lett. 2012, 14, 5428) that the halogenation of alcohols (e.g., 4 to 5) could be achieved with [Et2NSF2]BF4 (XtalFluor-E) in the presence of the appropriate tetraethylammonium halide. A method for the reductive bromination of carboxylic acid 6 to bromide 7 was developed (Org. Lett. 2012, 14, 4842) by Norio Sakai at the Tokyo University of Science. Professor Sakai also reported (Org. Lett. 2012, 14, 4366) a related method for the reductive coupling of acid 8 with octanethiol to produce thioether 9. The esterification of primary alcohols in water-containing solvent was achieved (Org. Lett. 2012, 14, 4910) by Michio Kurosu at the University of Tennessee Health Science Center using the reagent 11, such as in the conversion of alcohol 10 to produce 12 in high yield. Hosahudya N. Gopi discovered (Chem. Commun. 2012, 48, 7085) that the conversion of thioacid 13 to amide 14 was rapidly promoted by CuSO4. A ruthenium-catalyzed dehydrative amidation procedure using azides and alcohols, such as the reaction of 15 with phenylethanol to produce 16, was reported (Org. Lett. 2012, 14, 6028) by Soon Hyeok Hong at Seoul National University. An alternative oxidative amidation was developed (Tetrahedron Lett. 2012, 53, 6479) by Chengjian Zhu at Nanjing University and the Shanghai Institute of Organic Chemistry who utilized catalytic tetrabutylammonium iodide and disubstituted formamides to convert alcohols such as 17 to amides 18. A redox catalysis strategy was developed (Angew. Chem. Int. Ed. 2012, 51, 12036) by Brandon L. Ashfeld at Notre Dame for the triphenylphosphine-catalyzed Staudinger ligation of carboxylic acid 19 to furnish amide 20. For direct catalytic amidation of carboxylic acids and amines such as in the conversion of 21 to 23, Dennis G. Hall at the University of Alberta reported (J. Org. Chem. 2012, 77, 8386) that the boronic acid 22 was a highly effective catalyst that operated at room temperature.

Metal-Mediated Ring Construction: The Hoveyda Synthesis of (–)-Nakadomarin A

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Preliminary Investigation ◽  
State University ◽  
Colorado State University ◽  
Nakadomarin A ◽  
Sterically Demanding ◽  
National University ◽  
Rh Catalyst ◽  
Seoul National University ◽  
The University ◽  
Technological University

John F. Hartwig of the University of California, Berkeley effected (J. Am. Chem. Soc. 2013, 135, 3375) selective borylation of the cyclopropane 1 to give 2. It would be particularly useful if this borylation could be made enantioselective. Eric M. Ferreira of Colorado State University showed (Org. Lett. 2013, 15, 1772) that the enantomeric excess of 3 was transferred to the highly substituted cyclopropane 4. Antonio M. Echavarren of ICIQ Tarragona demonstrated (Org. Lett. 2013, 15, 1576) that Au-mediated cyclobutene construction could be used to form the medium ring of 6. Joseph M. Fox of the University of Delaware developed (J. Am. Chem. Soc. 2013, 135, 9283) what promises to be a general enantioselective route to cyclobutanes such as 8 by way of the intermediate bicyclobutane (not illustrated). Huw M.L. Davies of Emory University reported (Org. Lett. 2013, 15, 310) a preliminary investigation in this same direction. Masahisa Nakada of Waseda University prepared (Org. Lett. 2013, 15, 1004) the cyclopentane 10 by enantioselective cyclization of 9 followed by reductive opening. Young-Ger Suh of Seoul National University cyclized (Org. Lett. 2013, 15, 531) the lactone 11 to the cyclopentane 12. Xavier Ariza and Jaume Farràs of the Universitat de Barcelona optimized (J. Org. Chem. 2013, 78, 5482) the Ti-mediated reductive cyclization of 13 to 14. The hydrogenation catalyst reduced the intermediate Ti–C bond without affecting the alkene. Erick M. Carreira of ETH Zürich observed (Angew. Chem. Int. Ed. 2013, 52, 5382) that a sterically demanding Rh catalyst mediated the highly diastereoselective cyclization of 15 to 16. The ketone 16 was the key intermediate in a synthesis of the epoxyisoprostanes. Jianrong (Steve) Zhou of Nanyang Technological University used (Angew. Chem. Int. Ed. 2013, 52, 4906) a Pd catalyst to effect the coupling of 17 with the prochiral 18. Geum-Sook Hwang and Do Hyun Ryu of Sungkyunkwan University devised (J. Am. Chem. Soc. 2013, 135, 7126) a boron catalyst to effect the addition of the diazo ester 21 to 20. They showed that the sidechain stereocenter was effective in directing the subsequent hydrogenation of 22.

Enantioselective Construction of Alkylated Centers: The Shishido Synthesis of (+)-Helianane

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Allylic Alcohol ◽  
National University ◽  
Cu Catalyst ◽  
Rh Catalyst ◽  
Enantioselective Acylation ◽  
Enantioselective Addition ◽  
Institute Of Technology ◽  
Enantioselective Alkylation ◽  
Seoul National University ◽  
The University

Teck-Peng Loh of Nanyang Technological University developed (Org. Lett. 2011, 13, 876) a catalyst for the enantioselective addition of an aldehyde to the versatile acceptor 2 to give 3. Kirsten Zeitler of the Universität Regensburg employed (Angew. Chem. Int. Ed. 2011, 50, 951) a complementary strategy for the enantioselective coupling of 4 with 5. Clark R. Landis of the University of Wisconsin devised (Org. Lett. 2011, 13, 164) an Rh catalyst for the enantioselective formylation of the diene 7. Don M. Coltart of Duke University alkylated (J. Am. Chem. Soc. 2011, 133, 8714) the chiral hydrazone of acetone to give 9, then alkylated again to give, after hydrolysis, the ketone 11 in high ee. Youming Wang and Zhenghong Zhou of Nankai University effected (J. Org. Chem. 2011, 76, 3872) the enantioselective addition of acetone to the nitroalkene 12. Takeshi Ohkuma of Hokkaido University achieved (Angew. Chem. Int. Ed. 2011, 50, 5541) high ee in the Ru-catalyzed hydrocyanation of 15. Gregory C. Fu, now at the California Institute of Technology, coupled (J. Am. Chem. Soc. 2011, 133, 8154) the 9-BBN borane 18 with the racemic chloride 17 to give 19 in high ee. Scott McN. Sieburth of Temple University optimized (Org. Lett. 2011, 13, 1787) an Rh catalyst for the enantioselective intramolecular hydrosilylation of 20 to 21. Several general methods have been devised for the enantioselective assembly of quaternary alkylated centers. Sung Ho Kang of KAIST Daejon developed (J. Am. Chem. Soc. 2011, 133, 1772) a Cu catalyst for the enantioselective acylation of the prochiral diol 22. Hyeung-geun Park of Seoul National University established (J. Am. Chem. Soc. 2011, 133, 4924) a phase transfer catalyst for the enantioselective alkylation of 24. Peter R. Schreiner of Justus-Liebig University Giessen found (J. Am. Chem. Soc. 2011, 133, 7624) a silicon catalyst that efficiently rearranged the Shi-derived epoxide of 26 to the aldehyde 27. Amir H. Hoveyda of Boston College coupled (J. Am. Chem. Soc. 2011, 133, 4778) 28 with the alkynyl Al reagent 29 to give 30 in high ee. Kozo Shishido of the University of Tokushima prepared (Synlett 2011, 1171) 31 by the Mitsunobu coupling of m-cresol with the enantiomerically pure allylic alcohol.

C–H Functionalization: The Ono/Kato/Dairi Synthesis of Fusiocca-1,10(14)-diene-3,8β,16-triol

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Cytochrome P450 ◽  
Iron Catalyst ◽  
State University ◽  
Colorado State University ◽  
Carbon Carbon Bond ◽  
National University ◽  
Rh Catalyst ◽  
Hydride Abstraction ◽  
Osaka Prefecture ◽  
The University

Theodore A. Betley of Harvard University devised (J. Am. Chem. Soc. 2011, 133, 4917) an iron catalyst for inserting the nitrene from 2 into the C–H of 1 to give 3. Bernhard Breit of the Freiburg Institute for Advanced Studies uncovered (J. Am. Chem. Soc. 2011, 133, 2386) a Rh catalyst that effected the intriguing hydration of a terminal alkyne 4 to the allylic ester 5. Yian Shi of Colorado State University specifically oxidized (Org. Lett. 2011, 13, 1548) one of the two allylic sites of 6 to give 7. Kálmán J. Szabó of Stockholm University optimized (J. Org. Chem. 2011, 76, 1503) the allylic oxidation of 9 to 10, using the inexpensive sodium perborate. Masayuki Inoue of the University of Tokyo specifically carbamoylated (Tetrahedron Lett. 2011, 52, 2885) the acetonide 12 to give 14. Stephen Caddick of University College London added (Tetrahedron Lett. 2011, 52, 1067) the formyl radical from 15 to 16 to give 17. Ilhyong Ryu of Osaka Prefecture University and Maurizio Fagnoni of the University of Pavia employed (Angew. Chem. Int. Ed. 2011, 50, 1869) a related strategy to effect the net transformation of 18 to 20. There are many examples of the oxidation of ethers and amines to reactive intermediates that can go on to carbon–carbon bond formation. Ram A. Vishwakarma of the Indian Institute of Integrative Medicine observed (Chem. Commun. 2011, 47, 5852) that with an iron catalyst, the aryl Grignard 22 smoothly coupled with THF 21 to give 23. Gong Chen of Pennsylvania State University effected (Angew. Chem. Int. Ed. 2011, 50, 5192) specific remote C–H arylation of 24, leading to 26. Takahiko Akiyama of Gakushuin University established (J. Am. Chem. Soc. 2011, 133, 2424) conditions for intramolecular hydride abstraction, effecting the conversion of 27 to 28. C–H functionalization in nature is often mediated by cytochrome P450 oxidation. Zhi Li of the National University of Singapore showed (Chem. Commun. 2011, 47, 3284) that a particular cytochrome P450 selectively oxidized 29 to the alcohol 30, leaving the chemically more reactive benzylic position intact.

scholarly journals Predictors of cervical myelopathy and hydrocephalus in young children with achondroplasia

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Youngbo Shim ◽  
Jung Min Ko ◽  
Tae-Joon Cho ◽  
Seung‐Ki Kim ◽  
Ji Hoon Phi
Keyword(s):  
Magnetic Resonance Imaging ◽  
Young Children ◽  
Cervical Myelopathy ◽  
Treatment Method ◽  
Foramen Magnum ◽  
Resonance Imaging ◽  
Timely Manner ◽  
Frontal Horn ◽  
National University ◽  
Seoul National University

Abstract Background Cervical myelopathy and hydrocephalus occasionally occur in young children with achondroplasia. However, these conditions are not evaluated in a timely manner in many cases. The current study presents significant predictors for cervical myelopathy and hydrocephalus in young children with achondroplasia. Methods A retrospective analysis of 65 patients with achondroplasia who visited Seoul National University Children’s Hospital since 2012 was performed. The patients were divided into groups according to the presence of cervical myelopathy and hydrocephalus, and differences in foramen magnum parameters and ventricular parameters by magnetic resonance imaging between groups were analyzed. Predictors for cervical myelopathy and hydrocephalus were analyzed, and the cut-off points for significant ones were calculated. Results The group with cervical myelopathy showed foramen magnum parameters that indicated significantly lower cord thickness than in the group without cervical myelopathy, and the group with hydrocephalus showed significantly higher ventricular parameters and ‘Posterior indentation’ grade than the group without hydrocephalus. ‘Cord constriction ratio’ (OR 5199.90, p = 0.001) for cervical myelopathy and ‘Frontal horn width’ (OR 1.14, p = 0.001) and ‘Posterior indentation’ grade (grade 1: OR 9.25, p = 0.06; grade 2: OR 18.50, p = 0.01) for hydrocephalus were significant predictors. The cut-off points for cervical myelopathy were ‘Cord constriction ratio’ of 0.25 and ‘FM AP’ of 8 mm (AUC 0.821 and 0.862, respectively) and ‘Frontal horn width’ of 50 mm and ‘Posterior indentation’ grade of 0 (AUC 0.788 and 0.758, respectively) for hydrocephalus. Conclusion ‘Cord constriction ratio’ for cervical myelopathy and ‘Frontal horn width’ and ‘Posterior indentation’ grade for hydrocephalus were significant predictors and may be used as useful parameters for management. ‘Posterior indentation’ grade may also be used to determine the treatment method for hydrocephalus.

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