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Continuing developments in the elucidation techniques of complex catalytic processes is of foremost importance to modern synthetic chemistry, and the identification of efficient synthetic techniques relies on precise, reliable, and adaptable methods to dissect the mechanism of a given transformation. Currently, methods of reaction development are grounded upon the systematic modification of specific variables - such as temperature, time, concentration, etc. - to account for and control the dynamic series of coupled equilibria within a catalytic environment. On the other hand, tandem reaction analytical methods that involve the concomitant use of different instruments to probe a reaction can provide time-resolved information regarding active chemical species and facilitate the interrogation and optimization of the system. Herein, we report our study applying tandem in situ ReactIR and HPLC-MS monitoring to the dysprosium(III) triflate-catalyzed aza-Piancatelli rearrangement of 2-furylcarbinols, a reaction that grants access to trans-4,5-disubstituted cyclopentenones - common motifs in important biologically relevant and natural compounds. With a prototype automated sampling apparatus, information was obtained about the intrinsic chemoselectivity of the reaction, and previously unseen intermediates were observed, allowing for a more detailed reaction mechanism to be substantiated. The advantages of applying this type of tandem measurement to study these types of systems are also discussed. (Figure Presented).

The observed rate of reaction in the dysprosium triflate catalyzed aza-Piancatelli rearrangement is controlled by a key off-cycle binding between aniline and catalyst. Deconvoluting the role of these ancillary species greatly broadens our understanding of factors affecting the productive catalytic pathway. We demonstrate that the rate of reaction is controlled by initial competitive binding between the furylcarbinol and nitrogen nucleophile using either a Brønsted or Lewis acid catalyst and that the resulting rearrangement proceeds without involving the Brønsted and Lewis acid catalyst. This shows conclusively that the rate-controlling step and selectivity of reaction are decoupled.

Introduction: Moisturizers play an essential role in maintaining the integrity of the skin barrier by increasing stratum corneum hydration (SCH) and reducing transepidermal water loss (TEWL). According to dermatology and allergy guidelines, moisturizers should be applied on the skin within 3 min after bathing or showering. However, there is very little evidence supporting this recommendation. This study aimed to investigate the effectiveness of immediate and delayed moisturizing after bathing/washing on the improvement of SCH and TEWL., Methods: This was a crossover study of 60 healthy Vietnamese volunteers aged 18-25 years. In each subject, SCH and TEWL levels were measured at three areas: non-moisturized, immediate moisturizing after washing, and delayed moisturizing at 30 min after washing., Results: In non-moisturized skin, SCH and TEWL levels were significantly different from the baseline at 60 min after washing, while significantly decreased TEWL levels were observed immediately after moisturizing. In addition, moisturized skin had significantly higher SCH and lower TEWL levels compared with non-moisturized areas at every time point (p < 0.05). Interestingly, the percentage changes of SCH and TEWL levels from baseline did not differ between immediately and delayed moisturized areas., Conclusions: Tested moisturizer helped increase SCH and decrease TEWL; however, there was no difference in moisturizing effectiveness between immediate and delayed moisturizing in healthy skin. The recommendation of immediate application of moisturizers after bathing/washing should be reconsidered, and more studies are needed to establish a stronger recommendation., (© 2022 Wiley Periodicals LLC.)