We highlight the reported developments of the palladium-catalyzed C–H activation and functionalization of the inactive/unreactive prochiral C(sp3)–H bonds of aliphatic and alicyclic compounds. There exist numerous classical methods for generating...
This paper reports the synthesis of enantiopure aryl alkyl ethers via the Pd(II)-catalyzed picolinamide-aided γ-C(sp 2 )À H alkoxylation of various enantiopure α-alkylbenzylamine derivatives using alcohols. Enantiopure α-methylbenzylamines and amino alcohol substrates such as 2amino-2-phenylethanol (phenylglycinol) and 3-amino-3-phenylpropanol were subjected to the γ-C(sp 2 )À H alkoxylation (etherification) with alcohols using PIDA. α-Alkylbenzylamines and phenylglycinols are valuable building blocks in organic synthesis and medicinal chemistry research areas. Accordingly, this work has enabled the assembling of various enantiopure ortho-alkoxylated α-methylbenzylamine and 2-amino-2-phenylethanol (phenylglycinol) and 3-amino-3-phenylpropanol derivatives containing aryl alkyl ether functionality. We have shown the utility of ortho-alkoxylated αmethylbenzylamine derivatives for assembling enantiopure α-methylbenzylamine-based sulfamoylcarbamates and carboxamides which are structurally related to the bio-active compounds known in the literature. This work demonstrates the substrate scope elaboration in CÀ H functionalization and etherification through the CÀ O bond-forming process and synthesis of aryl alkyl ether functionality containing enantiopure α-alkylbenzylamines.
We report the Pd(II)-catalyzed picolinamide-aided ortho-CÀ H arylation-, alkylation-, and halogenation (sp 2 γÀ CÀ H functionalization) of phenylglycinol substrates. Phenylglycinols are remarkable building blocks and have found different applications in synthetic organic and medicinal chemistry. This work is a contribution towards the expansion of the library of phenylglycinol scaffolds and also substrate scope development by using the Pd(II)catalyzed bidentate directing group picolinamide-aided CÀ H activation tactic.
In this article, we discuss the recent developments in palladium (Pd)‐catalyzed C(sp
3
)H activation assisted by native directing groups. Although studies on preinstalled (exogenous) directing group‐aided Pd‐catalyzed C(sp
3
)H functionalization reactions are still emerging, research on Pd‐catalyzed C(sp
3
)H activation assisted by native directing groups is growing at a considerable pace. Native directing groups refer to inherent functional groups or moieties present in small organic molecules. Accordingly, this article presents developments involving the Pd‐catalyzed C(sp
3
)H functionalization of small organic molecules containing functional groups, such as carboxylic acid, amine, azaarene, ketone, and part of peptide moieties, which act as native directing groups.
An adaptive biased architecture of voltage differencing transconductance amplifier (AB-VDTA) with high transconductance gain is proposed in this paper. The proposed AB-VDTA is very efficient in terms of power. The structure proposed involves of two units namely two transconductance amplifiers (TAs) and two squarer. The bias current of the TA is made to vary with a square relation of the differential input voltage. Therefore, the proposed structure provides tunable gain depending on the input differential voltage. The proposed AB-VDTA exhibits improved transconductance gain, transient characteristics, reduced standby power dissipation and linearity for large range of inputs. The mathematical formulation has been presented to establish the characteristics of the proposed AB-VDTA. The proposed structure of AB-VDTA is validated through SPICE simulations using 180[Formula: see text]nm complementary metal oxide semiconductor (CMOS) technology. The proposed scheme has an edge over the existing ones as the outlined methods enhance the transconductance gain by increasing the bias current. The [Formula: see text] values are observed to be 2.3 and 1.4[Formula: see text]mS for proposed AB-VDTA and conventional VDTA, respectively, with the corresponding 3[Formula: see text]dB frequencies 620 and 348[Formula: see text]MHz. Therefore, 64% improvement in transconductance gain is recorded for same value of bias currents. The linear input range of TA1 is observed to be [Formula: see text][Formula: see text]mV and the overall linear range of the VDTA is [Formula: see text][Formula: see text]mV for the proposed AB-VDTA. The PVT analysis is carried out to show the effect of process corners. To check the robustness of the proposed VDTA, Monte Carlo analysis is performed, and results have been included in the form of histograms. As an application example, a current mode (CM) universal single input multiple output (SIMO) biquad filter is also designed using the proposed VDTA to show its usefulness, and a 2.7 times higher pole frequency is obtained at equal bias current.
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