ABSTRACT
Although the transition-metal-catalyzed vinylations of amines and alcohols via the additions to alkynes have been well developed, the selective vinylations of amino alcohols have been merely investigated. Herein, we report the gold-catalyzed divergent additions of trans-2-butene-1,4-amino alcohols' N-H and O-H groups to alkynes. The allyl enamine and allyl vinyl ether adducts then underwent a cascade (Aza-) Claisen rearrangement/cyclization sequence, furnishing the functionalized dihydropyrrole and dihydrofuran products.
ABSTRACT
BACKGROUND: To investigate the effect of virtual simulation systems on the teaching of inlay experiments and to guide the experimental teaching of tooth preparation. METHODS: Participants in their second semester of the junior year were selected to carry out the unified teaching and evaluation of dental preparation theory. The age varied from 18 to 22 years (19.96 ± 0.70) and the participants were randomly divided into four groups (n = 19) with a similar male-to-female ratio following CONSORT guidelines, including a jaw simulation model training group (Group J), a virtual simulation system training group (Group V), a jaw model training first followed by a virtual system training group (Group J-V), and a virtual system followed by a jaw model training group (Group V-J). The inlay tooth preparation assessment was performed on the extracted teeth. The data were analysed according to the assessment scores by a senior clinician. The subjective feelings of the students towards the system were evaluated using questionnaires. RESULTS: The second theoretical scores of Group V-J (63.5 ± 2.89) and Group J-V (60.5 ± 3.25) were higher than those of Group V (57.5 ± 3.13) and Group J (58.0 ± 3.67). The experimental scores of Groups J-V and V-J (62.79 ± 2.84; 64.00 ± 2.85) were higher than those of Groups V and J (56.05 ± 3.39; 55.74 ± 2.53). The questionnaire survey illustrated that most students preferred the digital virtual simulation system (perfect assessment: 91.3%, accuracy: 82.6%, satisfaction: 52.2%). CONCLUSION: Virtual simulation training can facilitate the teaching effect of tooth preparation in inlay experiments, and the teaching mode of Group V-J was the best. Therefore, this teaching mode is to be popularised.
Subject(s)
Educational Measurement , Simulation Training , Male , Female , Humans , Adolescent , Young Adult , Adult , Computer Simulation , User-Computer Interface , TeachingABSTRACT
Diaryliodonium salts have been extensively applied in organic synthesis as aryl cation equivalents. However, in the electrophilic reactions with alkenes or alkynes, only the electrophilic carbon of the diaryliodonium salts was involved while the other part of the aryl ring was not utilized. Herein, a reaction pattern of diaryliodonium was reported as oxa-1,4-dipoles to undergo (4 + 2) cycloaddition reactions with alkynes. Broad spectrum of the two reaction partners could be utilized in this protocol, enabling an operationally simple, high yielding, and regioselective synthetic approach to isocoumarins. Particularly, good to excellent regioselectivities were achieved for the sterically unbiased unsymmetrical diaryl acetylenes, which was challenging for other transition metal-catalyzed processes. The reaction could be scaled up with the ideal 1:1 stoichiometry and the isocoumarin type natural products Oospolactone and Thunberginol A could be obtained in one or three steps through this methodology.
ABSTRACT
Vinyl triflimides were only accessible recently and their chemistry is yet to be discovered. Herein, we describe a general, straightforward and atom-economical synthesis of these materials from alkynes and triflimide. A vast array of terminal and internal alkynes with broad spectrum of functionalities could be employed to generate various di- and trisubstituted vinyl triflimides regiospecifically with high to specific stereoselectivity. Moreover, the protocol could be conducted on gram scale using terminal and internal alkynes. Preliminarily attempts to probe the unprecedented reactivity of vinyl triflimides revealed part of its chemical properties.
