- Chemoselective reduction of isothiocyanates to thioformamides mediated by the Schwartz reagent
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Thioformamides are easily prepared-under full chemocontrol-through the partial reduction of isothiocyanates with the in situ generated Schwartz reagent. The high electrophilicity of the starting materials enables the straightforward addition of the hydride ion, thus constituting a reliable and high-yielding method for obtaining variously functionalized thioformamides. Sensitive chemical groups to the reduction conditions such as nitro, ester, alkene, azo, azide and keto groups do not interfere with the chemoselectivity of the process. Moreover, the stereochemical information embodied in the starting material is fully retained in the final products. The synthetic potential of the selected thioformamide template is also briefly discussed.
- De La Vega-Hernández, Karen,Senatore, Raffaele,Miele, Margherita,Urban, Ernst,Holzer, Wolfgang,Pace, Vittorio
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supporting information
p. 1970 - 1978
(2019/02/20)
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- Efficient Cs2CO3-promoted solution and solid phase synthesis of carbonates and carbamates in the presence of TBAI
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Novel solution and solid-phase methods for the synthesis of carbonates and carbamates were developed using cesium bases and TBAI via a three-component coupling. Cesium carbonate not only promoted successful carbonylations of alcohols and carbamations of amines, but also suppressed common side reactions traditionally seen using existing protocols. Various alcohols and amines were examined, using a wide array of alkyl halides, and the results demonstrated this methodology was highly chemoselective. In particular, use of either sterically demanding substrates or amino acid derivatives afforded the corresponding products exclusively, offering a wide variety of applications such as novel protecting groups and peptidomimetic syntheses.
- Salvatore, Ralph N,Chu, Feixia,Nagle, Advait S,Kapxhiu, Elona A,Cross, Richard M,Jung, Kyung Woon
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p. 3329 - 3347
(2007/10/03)
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- Cephem compounds having a terminal aminocarboxylic acid grouping and containing an azacyclyl(thio)ureido group
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Compounds of the formula STR1 in which the index n represents an integer of from 1 to 4, the index m represents 0 or 1, X represents oxygen, sulphur or the group --NH--, W represents a group --CO--, --CO--NHSO2 -- or --SO2 NH--CO--, or X-W together represent a group --CO-- or --CO--NHSO2 --, A represents optionally substituted phenylene, thienylene or furylene, Z represents oxygen or sulphur, Y represents lower alkylene, the index k represents the value 1 or 2, R4 represents hydrogen, an optionally substituted lower aliphatic or cycloaliphatic radical or acyl, R1 represents hydrogen, lower alkyl, lower alkoxy, halogen or a group of the formula --CH2 --R2 in which R2 represents a free, esterified or etherified hydroxy or mercapto group or a quaternary ammonium group, and R3 represents hydrogen or methoxy, and in which the carboxyl groups are optionally esterified in a form that can be split under physiological conditions, and salts of such compounds having salt-forming groups, are obtained by liberating the functional group(s) in a compound of the formula I in which at least one of the functional groups present is protected. The compounds are effective in vitro and in vivo against gram-positive and gram-negative bacteria and cocci.
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- META FUNCTIONALIZATION OF ANILINES AND PHENOL
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Regioselective introduction of various functional groups on the meta-position of anilines and phenol was achieved by proton abstraction from chromium tricarbonyl complexes 3,5,7 with n-BuLi, followed by the addition of electrophiles and decomplexation.
- Fukui, Mineo,Ikeda, Toshiya,Oishi, Takeshi
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p. 1605 - 1608
(2007/10/02)
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