Oxidative Dearomatization of Pyridines.

Dearomatization of pyridines is a well-established synthetic approach to access piperidines. Although remarkably powerful, existing dearomatization processes have been limited to the hydrogenation or addition of carbon-based nucleophiles to activated pyridiniums. Here, we show that arenophile-mediated dearomatizations can be applied to pyridines to directly introduce heteroatom functionalities without prior substrate activation. The arenophile platform in combination with olefin oxidation chemistry provides access to dihydropyridine cis-diols and epoxides. These previously elusive compounds are now readily accessible and can be used for the downstream preparation of diversely functionalized piperidines.

Electrochemical Dearomatization of Commodity Polymers.

Dearomatizations are widely adopted strategies in synthetic organic chemistry that convert arenes into compounds of broader utility; however, these transformations are virtually nonexistent in macromolecular chemistry. Herein, we report the first systematic investigations into electroreductive dearomatization of common polymers, delivering polyolefinic materials without significant molecular weight changes across several orders of magnitude (103-106 Da) and with a controlled and broad range of reduction. The dearomatized and further elaborated products provided new material space that could not be obtained by using any existing polymerization or functionalization methods. This study also represents a rare example of solution-based electrosynthesis involving macromolecules and revealed an interesting electrochemical phenomenon between the molecular weight of polymer and conversion.

Chemical Equivalent of Arene Monooxygenases: Dearomative Synthesis of Arene Oxides and Oxepines.

Direct epoxidation of aromatic nuclei by cytochrome P450 monooxygenases is one of the major metabolic pathways of arenes in eukaryotes. The resulting arene oxides serve as versatile precursors to phenols, oxepines, or trans-dihydrodiol-based metabolites. Although such compounds have an important biological and chemical relevance, the lack of methods for their production has hampered access to their utility. Herein, we report a general arenophile-based strategy for the dearomative synthesis of arene oxides. The mildness of this method permits access to sensitive monocyclic arene oxides without any noticeable decomposition to phenols. Moreover, this method enables direct conversion of polycyclic arenes and heteroarenes into the corresponding oxepines. Finally, these studies provided direct connection between simple aromatic precursors and complex small organic molecules via arene oxides and oxepines.

Development of a Scalable and Sublimation-Free Route to MTAD.

The cyclic azodicarbonyl 4-methyl-1,2,4-triazoline-3,5-dione (MTAD) is a versatile and powerful reagent used mainly in cycloaddition chemistry. Though known for more than 50 years, its unsafe preparation, as well as purification by sublimation, hampered its widespread applicability on a larger scale. Herein we report a scalable and safe route to MTAD, which avoids the generation of methyl isocyanate. Moreover, we demonstrate that sublimation can be circumvented by the application of judicious oxidation conditions, followed by simple filtration. Overall, up to 25 g of MTAD was prepared in a single batch from commercial starting materials in three steps, with recrystallization serving as the only purification in the sequence. When employed in dearomative methodologies, the MTAD obtained by this protocol displayed synthetic efficiency equivalent to that of MTAD purified by sublimation.

A melt castable energetic cocrystal.

An energetic cocrystal is described between 3,4-diaminofurazan (DAF) and 4-amino-3,5-dinitropyrazole (ADNP). The material is remarkable because interaction between the components leads to melting behavior and melt-state stabilization (absent in ADNP), that allows a melt castable formulation with explosive performance superior to DAF. This provides another potential advantage of cocrystallization for energetic materials.

Manipulating instructions strategically affects reliance on the ventral-lexical reading stream: converging evidence from neuroimaging and reaction time.

Neurobiology of reading research has yet to explore whether reliance on the ventral-lexical stream during word reading can be enhanced by the instructed reading strategy, or whether it is impervious to such strategies. We examined Instructions: name all vs. name words (based on spelling), Word Type: regular words vs. exception words, and Word Frequency (WF) in print (log10 HAL WF) in an experiment while measuring fMRI BOLD and overt naming reaction time (RT) simultaneously. Instructions to name words increased overall reliance on the ventral-lexical stream, as measured by visible BOLD activation and the WF effect on RT, with regular words showing the greatest effects as a function of this reading strategy. Furthermore, the pattern of joint effects of these variables on RT supports the notion of cascaded, not parallel, processing. These results can be accommodated by dual-stream cascaded models of reading, and present a challenge to single-mechanism parallel processing models.