4458-64-4Relevant academic research and scientific papers
Enantioselective Synthesis of Cyclopropanone Equivalents and Application to the Formation of Chiral β-Lactams
Jang, Yujin,Johnson, J. Drake,Jung, Myunggi,Lindsay, Vincent N. G.,Poteat, Christopher M.,Williams, Rachel G.
supporting information, p. 18655 - 18661 (2020/08/21)
Cyclopropanone derivatives have long been considered unsustainable synthetic intermediates because of their extreme strain and kinetic instability. Reported here is the enantioselective synthesis of 1-sulfonylcyclopropanols, as stable yet powerful equivalents of the corresponding cyclopropanone derivatives, by α-hydroxylation of sulfonylcyclopropanes using a bis(silyl) peroxide as the electrophilic oxygen source. This work constitutes the first general approach to enantioenriched cyclopropanone derivatives. Both the electronic and steric nature of the sulfonyl moiety, which serves as a base-labile protecting group and confers crystallinity to these cyclopropanone precursors, were found to have a crucial impact on the rate of equilibration to the corresponding cyclopropanone. The utility of these cyclopropanone surrogates is demonstrated in a mild and stereospecific formal [3+1] cycloaddition with simple hydroxylamines, leading to the efficient formation of chiral β-lactam derivatives.
A New Approach Using Aromatic-Solvent-Induced Shifts in NMR Spectroscopy to Analyze β-Lactams with Various Substitution Patterns
Chavelas-Hernández, Leticia,Dominguez-Mendoza, Blanca E.,Escalante, Jaime,Hernández-Vázquez, Luis G.,Valdéz-Camacho, Jonathan R.,Vasquez-Ríos, María G.
supporting information, p. 158 - 164 (2020/01/23)
The chemical shifts of protons depend not only on the properties of the solute molecule but also on the medium in which the solute resides. A series of β-lactams with various substitution patterns were synthesized to study aromatic-solvent-induced shifts
RuO4-mediated oxidation of N-benzylated tertiary amines. Four- And three-membered azacycloalkanes as substrates
Florea, Cristina A.,H?rtopeanu, Anca,Stavarache, Cristina,Petride, Horia
, p. 294 - 307 (2018/11/26)
Similarly to N-benzylpiperidine and -pyrrolidine, N-benzylazetidine underwent RuO4-catalyzed oxidation by attack at both types of N-methylene C-H bonds: Endocyclic and exocyclic (benzylic). If the reaction is performed in the presence of cyanide, α-aminon
Reductive alkylation of thioamides with Grignard reagents in the presence of Ti(O i Pr)4: Insight and extension
Hermant, Fabien,Urbaska, Ewelina,Seizilles De Mazancourt, Sarah,Maubert, Thomas,Nicolas, Emmanuel,Six, Yvan
supporting information, p. 5643 - 5653 (2015/02/19)
The reductive alkylation of thioamides by Grignard reagents in the presence of Ti(OiPr)4 is the subject of a study involving 20 different substrates. The influence of various parameters has been evaluated, showing notably that the yields of this moderately efficient process can be improved in several cases by applying a slow addition of the Grignard reagent. The results presented in this contribution also provide new insight into the reactivity of the proposed key intermediates, namely, a metalated iminium species and, ultimately, an α-metalated amine. Interestingly, by control of the temperature and the amount of Grignard reagent engaged, the reaction can be directed toward the selective formation of the former titanium intermediate complex. This represents an extension of the original method, allowing the synthesis of various previously inaccessible substituted amines by subsequent addition of a nucleophilic reagent. This role can be played not only by organomagnesium compounds but also by alkyllithium reagents, alkyltitanium(IV) complexes, and lithium aluminum hydride. The properties of the α-metalated amine final intermediate have also been explored, demonstrating that this complex is a poor nucleophile but can act as a radical precursor, which is especially evidenced when the resulting radical species are stabilized. Overall, this chemistry thus proves unexpectedly rich and can plausibly lay the basis for the development of new applications in the future.
Access to β-lactams by enantioselective palladium(0)-catalyzed C(sp3)-H alkylation
Pedroni, Julia,Boghi, Michele,Saget, Tanguy,Cramer, Nicolai
supporting information, p. 9064 - 9067 (2014/09/17)
β-Lactams are very important structural motifs because of their broad biological activities as well as their propensity to engage in ring-opening reactions. Transition-metal-catalyzed C-H functionalizations have emerged as strategy enabling yet uncommon h
Formation of acridones by ethylene extrusion in the reaction of arynes with β-lactams and dihydroquinolinones
Fang, Yuesi,Rogness, Donald C.,Larock, Richard C.,Shi, Feng
experimental part, p. 6262 - 6270 (2012/09/22)
N-Unsubstituted β-lactams react with a molecule of aryne by insertion into the amide bond to form a 2,3-dihydroquinolin-4-one, which subsequently reacts with another molecule of aryne to form an acridone by extrusion of a molecule of ethylene. 2,3-Dihydroquinolin-4-ones react under the same reaction conditions to afford identical results. This is the first example of ethylene extrusion in aryne chemistry.
Microwave-assisted synthesis of β-lactams and cyclo-β-dipeptides
Hernández-Vázquez, Luis G.,Leyva, Marco A.,Metta-Maga?a, Alejandro J.,Escalante, Jaime
, p. 2218 - 2230 (2013/02/22)
Different cyclo-β-dipeptides were prepared from corresponding N-substituted β-alanine derivatives under mild conditions using PhPOCl 2 as activating agent in benzene and Et3N as base. To evaluate β3-substituent influence,
Reactions of cyclopropanone acetals with alkyl azides: Carbonyl addition versus ring-opening pathways
Grecian, Scott,Desai, Pankaj,Mossman, Craig,Poutsma, Jennifer L.,Aube, Jeffrey
, p. 9439 - 9447 (2008/03/14)
(Chemical Equation Presented) The Lewis acid-mediated reactions of substituted cyclopropanone acetals with alkyl azides were found to strongly depend on the structure of the ketone component. When cyclopropanone acetal was treated with alkyl azides, N-substituted 2-azetidinones and ethyl carbamate products were obtained, arising from azide addition to the carbonyl, followed by ring expansion or rearrangement, respectively. When 2,2-dimethylcyclopropanone acetals were reacted with azides in the presence of BF3· OEt2, the products obtained were α-amino-α′- diazomethyl ketones, which arose from C2-C3 bond cleavage of the corresponding cyclopropanone, giving oxyallyl cations that were captured by azides. Aryl-substituted cyclopropanone acetals, when subjected to these conditions, afforded [1,2,3]oxaborazoles exclusively, which were also the result of C2-C3 bond rupture, azide capture, and then loss of nitrogen. In the reactions of n-hexyl-substituted cyclopropanone acetals with alkyl azides, a mixture of 2-azetidinones and regioisomeric [1,2,3]-oxaborazoles was obtained. The reasons for the different behavior of the various systems are discussed.
Use of 2,2′-dibenzothiazolyl disulfide-triphenylphosphine and Lawesson's Reagent in the cyclization of β-amino acids
Kanwar, Seema,Sharma
, p. 1748 - 1752 (2007/10/03)
The disulfide reagents 2,2′-dithiobisbenzothiazole (MBTS) and 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (Lawesson's Reagent, LR) mediate the cyclization of β-amino acids with remarkable product yields. Compared to other cyclodehydrating agents, these have been found to be superior in terms of their cost, making them industrially viable. The advantageous properties of MBTS and LR make them useful and unique additions to the arsenal of cyclodehydrating agents.
A new three-component cascade reaction to yield 3-spirocyclopropanated β-lactams
Zanobini, Alessandra,Brandi, Alberto,De Meijere, Armin
, p. 1251 - 1255 (2007/10/03)
A one-pot three-component reaction for the direct conversion of certain alkylhydroxylamine hydrochlorides 8 (alkyl = benzyl, p-methoxybenzyl, benzhydryl, tert-butyl), formaldehyde (9) or an alkyl glyoxylate (10) and bicyclopropylidene (2) to furnish 3-spi
