ABSTRACT
An efficient aminofluorosulfonylation strategy was developed for the synthesis of various pyrazoline-functionalized aliphatic sulfonyl fluorides using ß,γ-unsaturated hydrazones with sulfur dioxide and NFSI as the starting materials under mild conditions. The sulfonyl fluoride products could be successfully transformed into the corresponding sulfonate esters and amides via the sulfur(VI) fluoride exchange (SuFEx) click reactions. Preliminary mechanistic investigations demonstrate that the reaction operates through a radical cyclization/SO2 insertion/fluorination cascade process.
ABSTRACT
We present a facile switchable regioselective 7-endo or 6-exo iodocyclization of O-homoallyl benzimidates here, which affords various iodo-substituted 1,3-oxazines and tetrahydro-1,3-oxazepines in a controllable manner. The products can further undergo substitution reactions to afford a series of rich functionalized target heterocyclic molecules. The developed protocol has the advantages of mild conditions, simple operation, and excellent functional group compatibility.
ABSTRACT
Amines, especially those with multi-nitrogen moieties, are widespread in natural products and biologically active compounds. Thus, the development of direct and efficient methods to introduce multiple nitrogen-containing fragments into compounds in one step is highly desirable yet challenging. Herein, we report an NIS-promoted selective amino-diazidation and amino-iodoazidation of O-homoallyl benzimidates with NaN3. By using this protocol, a variety of vicinal diazido-substituted 1,3-oxazines and vicinal iodoazido-substituted 1,3-oxazines were directly synthesized in a controllable manner. Preliminary mechanistic investigations revealed that the reaction operates through a NIS-promoted four-step cascade process. The developed method has the merits of metal-free, excellent functional group compatibility, simple operation, and mild conditions.
Subject(s)
Amines , Oxazines , NitrogenABSTRACT
In this study, a 3 degree-of-freedom bionic waist joint was developed with coupled tendon-driven mechanism. This bionic waist joint can not only ensure the safety of the human-robot interface, but also increase the load capacity without increasing the weight. The coupled tendon-driven mechanism enables the motion of each joint to be driven by at least two motors together, and enables a maximum torque of 3 times the maximum motor output torque at each joint. The bionic waist joint has similar kinematic characteristics to a human waist, including degrees of freedom (DOF) and range of motion (ROM). The problem of coexistence of coupling and decoupling in the same rotating joint was solved with a novel mechanism that can promote further versatility of the coupled tendon-driven mechanism. The basic movements and characteristics of the waist was validated in the experiment.
Subject(s)
Bionics , Robotics , Biomechanical Phenomena , Humans , Movement , Range of Motion, ArticularABSTRACT
A practical electrophilic aminoselenation of O-homoallyl benzimidate with diselenides promoted by PhICl2/Cu2O has been developed. The easily available and stable diselenides were used as selenium sources. Various selenyl 1,3-oxazines, which are important frameworks in medicinal and biological chemistry, were easily obtained in moderate to good yields for the first time. Easy scaleup and scalability make this method attractive for the preparation of other valuable organoselenides.
ABSTRACT
A facile copper-catalyzed aminosulfonylation of O-homoallyl benzimidates with sodium sulfinates in the presence of tert-butyl peroxybenzoate (TBPB) and XPhos ligand has been developed. By using this protocol, a variety of potentially bioactive 1,3-oxazines were directly synthesized. This method has the merits of a cheap catalyst, easily available and stable sulfone reagents, and simple operation.
