Read by QxMD icon Read


Samuel L Bartlett, Kimberly M Keiter, Blane P Zavesky, Jeffrey S Johnson
A sequential benzoylation and multihetero-Cope rearrangement of α-keto ester derived nitrones has been developed. The reaction furnishes a diverse array of complex α-imino ester derivatives. The products can be transformed into amino alcohols via LiAlH4 reduction.
January 2019: Synthesis
Lukas Roiser, Katharina Zielke, Mario Waser
The formal (4+1)-cyclization between in situ generated achiral carbonyl-stabilized ammonium ylides and vinylogous p-quinone methides can be carried out under operationally simple conditions, leading to two different double bond regioisomers depending on the used conditions. Besides these racemic approaches, also a first proof-of-concept for enantioselective versions of these reactions has been obtained.
October 2018: Synthesis
Weiye Guan, Jennie Liao, Mary P Watson
Cross-couplings of benzylic pyridinium salts and vinylboronic acids or esters have been developed. Via these benzylic pyridinium intermediates, benzylic amines can be engaged in these cross-couplings via C-N bond functionalization. This method boasts mild reaction conditions and excellent tolerance for heteroaryl substituents and a range of functional groups.
August 2018: Synthesis
Leah M Stateman, Kohki M Nakafuku, David A Nagib
The selective functionalization of remote C-H bonds via intramolecular hydrogen atom transfer (HAT) is transformative for organic synthesis. This radical-mediated strategy provides access to novel reactivity that is complementary to closed-shell pathways. As modern methods for mild generation of radicals are continually developed, inherent selectivity paradigms of HAT mechanisms offer unparalleled opportunities for developing new strategies for C-H functionalization. This review outlines the history, recent advances, and mechanistic underpinnings of intramolecular HAT as a guide to addressing ongoing challenges in this arena...
April 2018: Synthesis
Joseph A Buonomo, Carter G Eiden, Courtney C Aldrich
A simple, one-pot, and high-yielding synthesis of 1,3-diphenyldisiloxane is presented. The preparation of similar symmetrical disiloxane materials is also accomplished with this same protocol. This mechano-chemical procedure is efficient and highly scalable, furnishing a convenient route to hydrido-disiloxanes from widely accessible commercially available silanes.
January 2018: Synthesis
Adrian G Amador, Evan M Sherbrook, Zhan Lu, Tehshik P Yoon
We report herein a method for intermolecular [3 + 2] cycloaddition between aryl cyclopropyl ketones and alkenes involving the combination of Lewis acid and photoredox catalysis. In contrast to other more common methods for [3 + 2] cycloaddition, these conditions operate using a broad range of both electron-rich and electron-deficient reaction partners. The critical factors predicting the success of these reactions is the redox potential of the cyclopropyl ketone and the ability of the alkene to stabilize a key radical intermediate...
2018: Synthesis
Kazuyuki Tokumaru, Kalisankar Bera, Jeffrey N Johnston
Umpolung Amide Synthesis (UmAS) has emerged as a superior alternative to conventional amide synthesis methods based on carbonyl electrophiles in a range of situations, particularly when epimerization-prone couplings are prescribed. In an unanticipated development during our most recent studies, it was discovered that diacyl hydrazide products from UmAS were not formed as intermediates when using an acyl hydrazide as the amine acceptor. This resulted in a new preparation of 1,3,4-oxadiazoles from α-bromonitroalkane donors...
October 2017: Synthesis
Arun K Ghosh, Anthony J Tomaine, Kelsey E Cantwell
Cyclic ethers are widely abundant in natural products. Cyclic ether templates are also utilized in drug design and medicinal chemistry. Although the synthetic processes for this class of compounds have been studied extensively with respect to five- and six-membered rings, medium-sized cyclic ethers are synthetically more challenging due to a variety of factors. Herein, we report our results on the Lewis acid catalyzed synthesis of medium-sized cyclic ethers in a diastereoselective manner.
September 2017: Synthesis
Scott E Denmark, Hyung Min Chi
Three general routes for the synthesis of ( E )-2-alkenyl-tethered anilines have been developed. The first route involves a 3-aza-Cope rearrangement of N -allylic anilines in the presence of a Lewis acid. The requisite N -allylic anilines were prepared by the addition of vinyl-magnesium reagents to the corresponding aldimines. The second route details a direct cross-metathesis of 2-allylic or 2-homoallylic anilines with styrenes. The third route involves a palladium-catalyzed C-N cross-coupling of aryl halides...
July 2017: Synthesis
Dian-Feng Chen, Tomislav Rovis
A chiral NHC/Brønsted acid cooperative catalysis system has been developed for asymmetric annulation of functionalized benzaldehydes and activated ketones through dearomative generation of dienolate.
January 2017: Synthesis
Cheng-Liang Zhu, Deng-Fu Lu, Jeffrey D Sears, Zhen-Xin Jia, Hao Xu
A set of practical synthetic procedures for the iron-catalyzed intermolecular olefin aminohydroxylation reactions in gram scale is reported. In these transformations, a bench-stable functionalized hydroxylamine is applied as the amination reagent. This method is compatible with a broad range of synthetically valuable olefins including those that are incompatible with the existing aminohydroxylation methods. It also provides valuable amino alcohol building blocks with regio- and stereo-chemical arrays that are complementary to known methods...
September 2016: Synthesis
Kaluvu Balaraman, Max Moskowitz, Yang Liu, Christian Wolf
Sequential chlorination/fluorination of aromatic trifluoroacetylated ketones gives 1-aryl 2-chloro-2,4,4,4-tetrafluoro-butan-1,3-dione hydrates that are used for the synthesis of ketones and alkenes exhibiting a terminal bromochlorofluoromethyl group. The hydrates undergo detrifluoroacetylative cleavage and subsequent bromination in the presence of a copper(II)bisoxazoline catalyst, K2CO3 and NBS at room temperature. The corresponding bromochlorofluoromethyl ketones can be applied in Wittig and Horner-Wadsworth-Emmons reactions and dibromoalkenylations...
August 2016: Synthesis
Shi Chen, Mukulesh Mondal, Ahmad A Ibrahim, Kraig A Wheeler, Nessan J Kerrigan
A highly diastereoselective approach to dipropionate derivatives through Pd/C-catalyzed hydrogenation of enantioenriched E-ketene heterodimers is described. Catalytic hydrogenation of the E-isomer of ketene heterodimer β-lactones (12 examples) provides access to syn,anti-β-lactones (dipropionate derivatives) bearing up to three stereogenic centers (dr up to 49:1), and with excellent transfer of chirality (ee up to >99%).
August 2016: Synthesis
Anthony J Brockway, Casey C Cosner, Oleg A Volkov, Margaret A Phillips, Jef K De Brabander
An improved synthesis of MDL 73811 - a potent AdoMetDC (S-adenosylmethionine decarboxylease) inhibitor and anti-trypanosomal compound with in vivo activity has been completed in four steps from commercially available 2',3'- O -isopropylideneadenosine. Utilization of Mitsunobu chemistry was crucial for the reliable and scalable introduction of the 5'-methylamine moiety, which was problematic using traditional activation/displacement chemistry as previously reported. All reactions in this synthesis were run on gram-scale resulting in a five-fold increase in yield over the original synthesis...
July 2016: Synthesis
Christian Riml, Ronald Micura
We report on the syntheses of 5-hydroxymethyl-uridine [5hm(rU)] and -cytidine [5hm(rC)] phosphoramidites and their incorporation into RNA by solid-phase synthesis. Deprotection of the oligonucleotides is accomplished in a straightforward manner using standard conditions, confirming the appropriateness of the acetyl protection used for the pseudobenzylic alcohol moieties. The approach provides robust access to 5hm(rC/U)-modified RNAs that await applications in pull-down experiments to identify potential modification enzymes...
April 2016: Synthesis
Yahaira Reyes, Keith T Mead
A study of cyclopropanations of oxy-substituted ethenes with ethyl α-diazoaroyl acetates is described. Whereas trimethylsilyl vinyl ether and ethyl vinyl ether gave dihydrofuran products, stable cyclopropanes were isolated when vinyl acetate was used. Yields ranged from 0-87%, depending on the nature and position of the aryl ring substituent.
October 2015: Synthesis
Jun-Shan Tian, Cheng-Liang Zhu, Yun-Rong Chen, Hao Xu
A new iron-catalyzed diastereoselective aminobromination method is reported for both internal and terminal olefins (yield up to 90% and dr up to >20:1). In this transformation, a functionalized hydroxylamine and bromide ion were used as the nitrogen and bromine source, respectively. This method is compatible with a broad range of olefins and provides a convenient approach to synthetically valuable vicinal bromo primary amines. Our studies suggest that both the diastereoselectivity and enantioselectivity for the olefin aminobromination can be controlled by iron catalysts...
June 2015: Synthesis
Mark W Irvine, Guangyu Fang, Richard Eaves, Maria B Mayo-Martin, Erica S Burnell, Blaise M Costa, Georgia R Culley, Arturas Volianskis, Graham L Collingridge, Daniel T Monaghan, David E Jane
9-Substituted phenanthrene-3-carboxylic acids have been reported to have allosteric modulatory activity at the NMDA receptor. This receptor is activated by the excitatory neurotransmitter L-glutamate and has been implicated in a range of neurological disorders such as schizophrenia, epilepsy and chronic pain and neurodegenerative disorders such as Alzheimer's disease. Herein, the convenient synthesis of a wide range of novel 3,9-disubstituted phenanthrene derivatives starting from a few common intermediates is described...
June 1, 2015: Synthesis
Casi M Schienebeck, Wangze Song, Angela M Smits, Weiping Tang
Various 3-acyloxy-1,4-enynes could be employed in rhodium-catalyzed intermolecular [5+1] and [5+2] cycloadditions with CO or alkynes, respectively. The rate of these cycloadditions could be accelerated significantly by using 1,4-enynes with an electron-donating ester on the 3-position. The scope of rhodium-catalyzed [5+1] and [5+2] cycloadditions were examined by using 1,4-enynes bearing an electron-donating ester.
May 2015: Synthesis
Arne R Philipps, Lars Fritze, Nico Erdmann, Dieter Enders
An organocatalytic quadruple cascade initiated by a Friedel-Crafts-type reaction is described. The (S)-diphenylprolinol trimethylsilyl ether catalyzed reaction yields highly functionalized cyclohexenecarbaldehydes bearing a 1,1-bis[4-(dialkylamino)phenyl]ethene moiety and three contiguous stereogenic centers. The reaction tolerates various functional groups and all products are obtained with very good diastereoselectivity and with virtually complete enantiomeric excess.
April 2, 2015: Synthesis
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"