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There are numerous methods in the literature for Direction-of-Arrival (DOA) estimation, including both classical and machine learning-based approaches that jointly estimate the Number of Sources (NOS) and DOA. However, most of these methods do not fully leverage the potential synergies between these two tasks, which could yield valuable shared information. To address this limitation, in this article, we present a multi-task Convolutional Neural Network (CNN) capable of simultaneously estimating both the NOS and the DOA of the signal. Through experiments on simulated data, we demonstrate that our proposed model surpasses the performance of state-of-the-art methods, especially in challenging environments characterized by high noise levels and dynamic conditions. [ABSTRACT FROM AUTHOR]

The reaction of alpha vinyl oxirane prepared through a new route to the D-gulal system, with O-nucleophiles and C-nucleophiles affords in a completely sterreoselective way, the corresponding 2-unsaturated alpha O-and C-glycosides having the same configuration as the starting epoxide.

A method for the synthesis of alpha-alkyl-gamma-hydroxy ketones was developed based on Sc(OTf)3-mediated reactions with lithium enolates. The addition reaction of lithium enolates with 1,2-epoxides proceeded efficiently in the presence of Sc(OTf)3 catalysts. The synthetic utility of the novel strategy was enhanced by the addition of active epoxides that mediate the formation of enantiopure compounds containing the gamma-hydroxy ketone skeleton. However, the synthetic process exhibited poor diastereoselectivity.

A method for the synthesis of alpha-alkyl-gamma-hydroxy ketones was developed based on Sc(OTf)3-mediated reactions with lithium enolates. The addition reaction of lithium enolates with 1,2-epoxides proceeded efficiently in the presence of Sc(OTf)3 catalysts. The synthetic utility of the novel strategy was enhanced by the addition of active epoxides that mediate the formation of enantiopure compounds containing the gamma-hydroxy ketone skeleton. However, the synthetic process exhibited poor diastereoselectivity.

The regiochemical outcome of the ring openings of cis- and trans-aziridines bearing a polar remote functionality were found to be dependant on the opening reaction conditions, whether standard, metal-assisted or strongly acidic. Therefore, the addition process can be almost completely controlled by regioalternating process. These results were determined in a conformationally semirigid bicyclic system in which the polar funtionality (OBn) is in a homoallylic relationship to the aziridine ring.

Flash chromatography separates cis- and trans epoxides occurring due to epoxidation of 2-(benzyloxy)-3,6-dihydro-2H-pyran with m-chloroperoxybenzoic acid. Ring-opening reactions of these epoxides with various nucleophiles reveal that a change from non-chelating to chelating conditions influences the regioselectivity. GC and NMR analyses reveal the amounts of regioisomeric products.

The synthesis and nucleophilic reactions of 2, 3-epoxy-1-alkanols allow a regiochemical study on the effect of remote polar functionalities on epoxide ring opening. The study shows that metal (Li+, Mg2+, Zn2+) chelation provides better, sometimes complete, C-3 regioselectivity than nonchelating cleavage conditions. Under chelation conditions, trans-epoxides show higher C-3 selectivity than cis-epoxides. Contrary to previous findings, free hydroxyls are not needed for chelation-controlled regioselectivity.

The synthesis of cis- and trans-3-(benzyloxymethyl)-1, 2-epoxycyclohexanes allows the study of their nucleophilic addition reactions. In the presence of a metallic salt catalyst, the cis-epoxide forms chelate intermediates which invite a nucleophilic attack on the C-1 oxirane carbon, resulting in ring cleavage. Its preference for chelation thus sterically directs the site of cleavage. The trans-epoxide, on the other hand, is prevented from undergoing chelation reactions due to its conformation. Its ring opening reactions are based on steric factors alone.

The synthesis of cis- and trans-epoxides of five 4-substituted cyclohexanes leads to a stereochemical study of their ring-opening reactions with various nucleophiles. The study shows that ring opening of the trans-epoxides is influenced by a mix of stereoelectronic and conformational factors. The cis-epoxides, on the other hand, are affected in varying degrees by chelation of a metal ion by the epoxide oxygen and that of the C-4 substitutent. The chelation effect depends on the reaction conditions and on the nature and concentration of the metal ion. The carboxylic acid derivative is also affected by hydrogen bonding.

[beta]-Phenylselenoglycosides are stereoselectively prepared by direct oxidative glycosylation of benzenselenolate (Ph[Se.sup.-]) with glycals. A rationalization of the [beta]-selectivity and the opposite [alpha]-selectivity reported in the ring-opening of epoxy glycals with benzeneselenol (PhSeH) is described.

A new stereoselective synthesis approach to substituted 3-aryl-2,3-dihydrobenzofurans by intramolecular cyclization of hydroxyphenols is described.

The reaction of the new D-galactal-derived allylic aziridine with O-nucleophiles affords, in a high to complete beta-stereoselectivity, the corresponding 2,3-unsaturated-beta-O-glycosides bearing a beta-N-functionality at C(4). The results indicate that in glycal-derived vinyl aziridine systems the configuration beta or alpha of the aziridine ring and the related coordination effects are responsible for almost complete beta- or alpha- stereoselectivity, observed in the completely regioselective conjugate addition of O-nucleophiles.

6-O-Trityl- and 6-(O-benzyl)-substituted epoxide derived from D-glucal are examined in their addition reactions with O-, C-, N-, and S-nucleophiles. Depending on the ability of the nucleophile to coordinate with the oxirane oxygen, a 1,4-regio- and beta-stereoselective or an anti 1,2-addition pathway is commonly observed.

A novel regiodivergent kinetic resolution of a series of allylic epoxides with alkylzinc reagents is described. The results demonstrate the potential of chiral copper-phosphoramidite catalysts-stereoregulated synthesis of cyclic and homoallylic alcohols with optical purities.

The geometry of the transition state involved in addition reactions of lithium enolate derived from propiophenone to propene oxide, are examined. The different reaction pathways involving TSs for the addition reaction of monomeric lithium are described.