A mild and efficient chemoselective N-deacetylation using the Schwartz reagent at room temperature in rapid time is described. The mild and neutral conditions enable orthogonal N-deacetylation in the presence of some of the common protecting groups (viz. Boc, Fmoc, Cbz, Ts). The deprotection conditions did not induce any epimerization at the chiral amino centre.
The Burgess reagent ([methoxycarbonylsulfamoyl]triethylammonium hydroxide) has historically found utility as a dehydrating agent. Herein we show that, in the presence of dimethyl sulfoxide, the Burgess reagent efficiently and rapidly facilitates the oxidation of a broad range of primary and secondary alcohols to their corresponding aldehydes and ketones in excellent yields and under mild conditions, and can be combined with other transformations (e.g., Wittig olefinations). A mechanism similar to those described for the Pfitzner-Moffatt and Swern oxidations is proposed.
The synthesis and study of al ibrary of cyclic (aryl)(amido)carbenes (CArAmCs), whichrepresent aclass of electrophilic NHCs that feature lowc alculated singlet-triplet gaps (DE ST = 19.9 kcal mol À1 ;B3LYP/def2-TZVP) and exhibit reactivity profiles expected from triplet carbenes,are described. The electrophilic properties of the CArAmCs were quantified by analyzing their respective selenium adducts,whichexhibited the largest downfield 77 Se NMR chemical shifts (up to 1645 ppm) measured for any NHC derivative knownt od ate, as well as their Ir carbonyl complexes,f rom whichl arge Tolman electronic parameter (TEP) values (up to 2064 cm À1 ) were ascertained. The CArAmCs were found to engage in reactions that are typically observed with triplet carbenes, including C À Hinsertions,[2+ +1] cycloadditions with alkenes as well as alkynes,a nd spontaneous oxidation upon exposure to oxygen.
Adamantyl vinyl ketone (AVK) and its copolymers are synthesized using reversible addition fragmentation chain‐transfer (RAFT) methodology and then degraded using UV light. The polymerization of AVK is found to be controlled as indicated by a linear correlation between the molecular weights of the polymers produced and monomer conversion as well as a series of chain extensions. The RAFT method is also used to synthesize random and block copolymers of AVK and methyl methacrylate. Irradiating poly(adamantyl vinyl ketone) (PAVK) with UV light affords a polyolefin and adamantane as the major products. Similar products are obtained, along with poly(methyl methacrylate) (PMMA), when the block copolymer is subjected to UV light. The random copolymer undergoes complete degradation under similar conditions. A mechanism wherein stereoelectronic effects channel photodegradation through Norrish I Type pathways in a manner that preserves the main chain of the polymer during the decomposition process is proposed.
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