The enantioselective electrochemical lactonization of diketo acid derivatives using chiral iodoarenes as redox mediators is reported for the first time. Good to high stereoselectivities are observed in the lactonization and also in intermolecular α-alkoxylations of diketo ester derivatives. This enantioselective process was then adapted to an electrochemical flow microreactor where only small amounts of supporting electrolyte were necessary.
BackgroundEmotions play a decisive and central role in the workplace, especially in the service-oriented enterprises. Due to the highly participatory and interactive nature of the service process, employees’ emotions are usually highly volatile during the service delivery process, which can have a negative impact on business performance. Therefore, it is important to effectively judge the emotional states of customer service staff.MethodsWe collected data on real-life work situations of call center employees in a large company. Three consecutive studies were conducted: first, the emotional states of 29 customer service staff were videotaped by wide-angle cameras. In Study 1, we constructed scoring criteria and auxiliary tools of picture-type scales through a free association test. In Study 2, two groups of experts were invited to evaluate the emotional states of customer service staff. In Study 3, based on the results in Study 2 and a multimodal emotional recognition method, a multimodal dataset was constructed to explore how each modality conveys the emotions of customer service staff in workplace.ResultsThrough the scoring by 2 groups of experts and 1 group of volunteers, we first developed a set of scoring criteria and picture-type scales with the combination of SAM scale for judging the emotional state of customer service staff. Then we constructed 99 (out of 297) sets of stable multimodal emotion datasets. Based on the comparison among the datasets, we found that voice conveys emotional valence in the workplace more significantly, and that facial expressions have more prominant connection with emotional arousal.ConclusionTheoretically, this study enriches the way in which emotion data is collected and can provide a basis for the subsequent development of multimodal emotional datasets. Practically, it can provide guidance for the effective judgment of employee emotions in the workplace.
A new synthesis of (+)-brefeldin A is reported via Padwa allenylsulfone [3 + 2]-cycloadditive elimination. Cycloadduct 13 was initially elaborated into iodide 27, which, following treatment with Zn, gave aldehyde 28 whose C(9) stereocenter was epimerized. Further elaboration into enoate 38 and Julia-Kocienski olefination with 5 subsequently afforded 39, which was deprotected at C(1) and O(15). Yamaguchi macrolactonization of the seco-acid thereafter afforded a macrocycle that underwent O-desilylation and inversion at C(4) to give (+)-brefeldin A following deprotection.
Selective oxidation of ring C-H bonds is an attractive route to functionalised cyclic amines which are versatile intermediates in drug synthesis and important fragment molecules in drug discovery. Here we report a combined substrate and enzyme engineering approach to achieve enantioselective functionalisation of all unactivated C-H bonds of azepane, azocane, 7azabicyclo[2.2.1]heptane, and 8-azaspiro[4.5]decane by cytochrome P450BM3 (CYP102A1).Different N-modifying groups provide product diversity at high enantioselectivity (up to 99% e.e.) from a panel of just 48 variants of P450BM3. Substrate docking into molecular dynamics simulation structures of enzyme variants is shown to be useful for designing mutations to increase enantioselectivity by disfavouring binding poses leading to the unwanted enantiomer, and to increase enzymatic activity by disfavouring non-productive poses from 10 or so variants per generation. The synthetic application of remote C-H activation within cyclic amines is exemplified by the synthesis of anisodamine via enantioselective hydroxylation of N-Bocnortropinone.
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