144039-24-7Relevant academic research and scientific papers
Guidelines for β-lactam synthesis: Glycal protecting groups dictate stereoelectronics and [2+2] cycloaddition kinetics
Grinstaff, Mark W.,Balijepalli, Anant S.,McNeely, James H.,Hamoud, Aladin
, p. 12044 - 12057 (2020/11/10)
The alkene-isocyanate cycloaddition method affords β- lactams from glycals with high regio- and stereoselectivity, but the factors that determine substrate reactivity are poorly understood. Thus, we synthesized a library of 17 electron-rich alkenes (glyca
Synthesis of Altrose Poly-amido-saccharides with β-N-(1→2)- d -amide Linkages: A Right-Handed Helical Conformation Engineered in at the Monomer Level
Xiao, Ruiqing,Dane, Eric L.,Zeng, Jialiu,McKnight, Christopher J.,Grinstaff, Mark W.
supporting information, p. 14217 - 14223 (2017/10/17)
The design and synthesis of amide-linked saccharide oligomers and polymers, which are predisposed to fold into specific ordered secondary structures, is of significant interest. Herein, right-handed helical poly amido-saccharides (PASs) with β-N-(1→2)-d-amide linkages are synthesized by the anionic ring-opening polymerization of an altrose β-lactam monomer (alt-lactam). The right-handed helical conformation is engineered into the polymers by preinstalling the β configuration of the lactam ring in the monomer via the stereospecific [2+2] cycloaddition of trichloroacetyl isocyanate with a d-glycal possessing a 3-benzyloxy group oriented to the α-face of the pyranose. The tert-butylacetyl chloride initiated polymerization of the alt-lactam proceeds smoothly to afford stereoregular polymers with narrow dispersities. Birch reduction of the benzylated polymers gives water-soluble altrose PASs (alt-PASs) in high yields without degradation of the polymer backbone. Circular dichroism analysis shows the alt-PASs adopt a right-handed helical conformation in aqueous solutions. This secondary conformation is stable over a wide range of different conditions, such as pH (2.0 to 12.0), temperature (5 to 75 °C), ionic salts (2.0 M LiCl, NaCl, and KCl), as well as in the presence of protein denaturants (4.0 M urea and guanidinium chloride). Cytotoxicity studies reveal that the alt-PASs are nontoxic to HEK, HeLa, and NIH3T3 cells. The results showcase the ability to direct solution conformation of polymers through monomer design. This approach is especially well-suited and straightforward for PASs as the helical conformations formed result from constraints imposed by the relatively rigid and sterically bulky repeating units.
CYCLOADDITION OF TRICHLOROACETYL ISOCYANATE TO GLYCALS
Chmielewski, Marek,Kaluza, Zbigniew
, p. 143 - 152 (2007/10/02)
Cycloaddition of trichloroacetyl isocyanate to 1,5-anhydro-2-deoxy-D-erythro- and -L-threo-pent-1-enitols, and 1,5-anhydro-2-deoxy-D- and -L-arabino-hex-1-enitols having benzyl, methyl, tert-butyldimethylsilyl, and trimethylsilyl substituents on hydroxyl groups proceeds satisfactorily, under normal pressure at room temperature, to give a mixture of and cycloadducts.The isocyanate enters the glycal molecule stereospecifically anti with respect to the C-3 substituent.Bicyclic adducts slowly rearrange to the respective α,β-unsaturated amides.N-Deprotection of the trichloroacetyl substituent in cycloadducts produces stable β-lactams.Further deprotection gives crystalline, water-soluble 2-carboxy-2-deoxypento- and -hexo-pyranosylaminolactams having a unique bicyclic sugar structure.
