Comparison of amine-induced cyclization of 6-chloro-1-hexynylphosphonate and isobutyl 7-chlorohept-2-ynoate

The reaction of 6-chloro-1-hexynylphosphonate with primary and secondary amines afforded exclusively 2-aminocyclohexenylphosphonates in 62-85% isolated yields. In contrast, reaction of various amines with isobutyl 7-chlorohept-2-ynoate in acetonitrile at 70 °C gave (E)-sec-butyl 2-(1-alkylpiperidin-2-ylidene)acetates in 65-78% isolated yields. Calculations offer an explanation for the difference in the behavior of the two compounds classes. It is shown that C-C cyclization in the alkyne-phosphonate group occurs via an initial formation of a zwitterionic intermediate, which is stabilized by both an inductive effect of the phosphonate group and a newly formed hydrogen bond. The alkyne-carboxylate group, on the other hand, proceeds via enamine formation as a result of the smaller inductive effect of the carboxylate combined with involvement of an allene-like resonance form. This resonance form both delocalizes the negative charge in the zwitterionic intermediate making it to be less available for attack, and affects the geometry thus preventing formation of the stabilizing hydrogen bond. Hence, the zwitterionic intermediate of the alkyne-carboxylates is less stable leading to formation of an enamine, which is followed by N-C cyclization to give the azaheterocycles.     

Fusion of artificial intelligence and game theory for resource allocation in non-orthogonal multiple access-assisted device-to-device cooperative communication

Device-to-device (D2D) communication offers a low-cost paradigm where two devices in close proximity can communicate without needing a base station (BS). It significantly improves radio resource allocation, channel gain, communication latency, and energy efficiency and offers cooperative communication to enhance the weak user's network coverage. The cellular mobile users (CMUs) share the spectral resources (e.g., power, channel, and spectrum) with D2D mobile users (DMUs), improving spectral efficiency. However, the reuse of radio resources causes various interferences, such as intercell and intracell interference, that degrade the performance of overall D2D communication. To overcome the aforementioned issues, this paper presents a fusion of AI and coalition game for secure resource allocation in non-orthogonal multiple access (NOMA)-based cooperative D2D communication. Here, NOMA uses the successive interference cancellation (SIC) technique to reduce the severe impact of interference from the D2D systems. Further, we utilized a coalition game theoretic model that efficiently and securely allocates the resources between CMUs and DMUs. However, in the coalition game, all DMUs participate in obtaining resources from CMUs, which increases the computational overhead of the overall system. For that, we employ artificial intelligence (AI) classifiers that bifurcate the DMUs based on their channel quality parameters, such as reference signal received power (RSRP), received signal strength indicator (RSSI), signal-to-noise ratio (SNR), and channel quality indicator (CQI). It only forwards the DMUs that have better channel quality parameters into the coalition game, thus reducing the computational overhead of the overall D2D communication. The performance of the proposed scheme is evaluated using various statistical metrics, for example, precision score, accuracy, recall, F1 score, overall sum rate, and secrecy capacity, where an accuracy of 99.38% is achieved while selecting DMUs for D2D communication.