A course is described where students are engaged in an inquiry-based quarter-long research project to synthesize a known pharmaceutical target. Students use literature search engines, such as Reaxys and SciFinder, and the primary chemical literature as resources to plan and perform the synthesis of their pharmaceutical target. Through this process, students develop critical thinking, problem solving, and data analysis skills in the laboratory setting. Teaching assistants guide students through three phases of the research process: (1) literature-based proposal, (2) experimentation and analysis, and (3) communication of research findings by oral presentation and written report. This course is designed for upper-division chemistry majors, taken as the third-quarter organic laboratory class after two quarters of introductory laboratory courses and two quarters of the associated organic chemistry lecture courses. Nine different teaching assistants have taught the course described to over 90 students in four different quarters.
It is demonstrated that nitrosocarbonyl hetero-Diels− Alder chemistry is an efficient and versatile reaction that can be applied in macromolecular synthesis. Polyethylene glycol functionalized with a hydroxamic acid moiety undergoes facile coupling with cyclopentadiene-terminated polystyrene, through a copper-catalyzed as well as thermal hetero-Diels−Alder reaction. The mild and orthogonal methods used to carry out this reaction make it an attractive method for the synthesis of block copolymers. The resulting block copolymers were analyzed and characterized using GPC and NMR. The product materials could be subjected to thermal retro [4 + 2] cycloaddition, allowing for the liberation of the individual polymer chains and subsequent recycling of the diene-terminated polymers.
a b s t r a c tPhotoredox catalysis is employed to generate highly reactive acylnitroso species from hydroxamic acid derivatives. The conditions are shown to be comparable to a previously developed transition metal aerobic oxidation and are amenable to a range of transformations including Diels-Alder and ene reactions. This unique application of such an approach gives access to temporal and spatial control in nitroso chemistry.Published by Elsevier Ltd.Nitrosocarbonyl compounds are exceptionally reactive intermediates that have found widespread use in a number of classic C-N or C-O bond-forming reactions, such as the ene, 14 Because nitrosocarbonyl compounds participate in a variety of organic reactions, the in situ formation of this highly reactive functional group using photoredox conditions would furnish a general procedure for patterning surfaces bearing a range of properties. Moreover, because nitrosocarbonyl compounds serve as HNO donors, 15 it could also provide a means to generate HNO in situ using visible-light to control its release. To evaluate this potential, we began by investigating the in situ generation of nitrosocarbonyl compounds using photoredox conditions. A recent report by Tan inspired us to disclose our results in this area (Fig. 1).
16Due to the transient nature of nitroso compounds and their associated inherent instability, 17 we selected the nitroso HDA reaction to test the feasibility of a photoredox catalyst system. Nitroso compounds directly attached to an electron withdrawing group undergo rapid [4+2] cycloaddition reactions with conjugated dienes, a reaction platform that has been explored extensively by our research group 2a and others. 18 Cbz-protected hydroxylamine 1 and 1,3-dicyclohexadiene 2 were elected as candidates for http://dx
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