Transition Metal Catalyzed Hiyama Cross-Coupling: Recent Methodology Developments and Synthetic Applications

Hiyama cross-coupling is a versatile reaction in synthetic organic chemistry for the construction of carbon-carbon bonds. It involves the coupling of organosilicons with organic halides using transition metal catalysts in good yields and high enantioselectivities. In recent years, hectic progress has been made by researchers toward the synthesis of diversified natural products and pharmaceutical drugs using the Hiyama coupling reaction. This review emphasizes the recent synthetic developments and applications of Hiyama cross-coupling.

An efficient synthesis of 4,5-diaryl-3,4-dihydropyrimidin-2(1H)-one via a cesium carbonate-promoted direct condensation of 1-aryl-2-propanone with 1,1′-(arylmethylene)diurea

An efficient method for the synthesis of 4,5-diaryl-3,4-dihydropyrimidin-2(1H)-one by using 1,1′-(arylmethylene)diurea and 1-aryl-2-propanone as substrates was developed. The reactions proceeded efficiently in the presence of Cs₂CO₃ to give the desired products in moderate to good yields with wide substrate scope and good functional group tolerance, serving as an attractive alternative or complement to the previously reported methods for the facile assembly of biologically and pharmaceutically active 3,4-dihydropyrimidin-2(1H)-ones.

A Cs₂CO₃-promoted efficient method for the synthesis of 4,5-diaryl-3,4-dihydropyrimidin-2(1H)-one by using 1,1′-(arylmethylene)diurea and 1-aryl-2-propanone as substrates was developed.

Sulfamic acid incorporated HKUST-1: a highly active catalyst and efficient adsorbent

Herein we introduce an effective approach for incorporating sulfamic acid (SA) into HKUST-1. The synthesized materials have been characterized using XRD, XPS, BET, FT-IR, SEM, EDX and TEM. The X-ray diffraction pattern of SA@HKUST-1 is analogous to that of parent HKUST-1 in line shape and d-spacing, proving that chemical modification could be obtained without damage to structural solidity. The XPS spectra confirmed successful sulfonation, due to the single S 2p peak being attributable to SO₃H groups at 168 eV. Catalytic efficiency was studied for 7-hydroxy-4-methyl coumarin and 3,4-dihydropyrimidinone synthesis and it was found to be highly dependent on the amount of SA loaded over HKUST-1. Moreover, the adsorptive removal activity of some common organic and inorganic pollutants from water has been studied. To fully understand the adsorption process, the effects of initial dye concentration, pH of solution, adsorbent dosage, contact time and temperature on the adsorption process were successfully studied. Under the optimum conditions 10 wt% SA@HKUST-1 was able to reach the maximum adsorption capacity for Pb²⁺ (298 mg g⁻¹) and Malachite green (290 mg g⁻¹). Hopefully, this will facilitate research on improving the prospective use of MOFs for future applications.

Herein we introduce an effective approach for incorporating sulfamic acid (SA) into HKUST-1.

Palygorskite-anchored Pd complexes catalyze the coupling reactions of pyrimidin-2-yl sulfonates

In this work, an anchored Pd complex (PGS–APTES–Pd(OAc)₂) was prepared via simple and green steps from the natural clay mineral palygorskite and was well characterized by XPS, XRD, IR, SEM, and EDX. This complex was further utilized as a fine catalyst for the C–C/C–N coupling reactions of pyrimidin-2-yl sulfonates. Subsequently, the cyclic utilization test indicated the high stability and sustainability of this PGS–APTES–Pd(OAc)₂ catalyst, and no activation was required in the recycling process, providing an applicable and reusable catalyst in organic synthesis.

PGS–APTES–Pd(OAc)₂ was prepared through simple and green steps from the natural clay mineral palygorskite. Obviously, the stability and reusability of PGS–APTES–Pd(OAc)₂ were superior to those of the PGS–Pd catalyst (prepared by the impregnation method) in recycling test.

Synthesis and fluorescence of pyrazolines substituted with pyrimidine and ferrocene subunits

1,3,5-Trisubstituted 2-pyrazolines were synthesized by the reaction of chalcones with hydrazine in hot ethanol. Their structures were elucidated by 1H NMR, 13C NMR, IR, MS and elemental analysis. The fluorescence spectra were measured in different organic solvents. The emission wavelength is blue shifted with the increase in solvent polarity.

An Efficient Amide-Aldehyde-Alkene Condensation: Synthesis for the N-Allyl Amides

The allylamine skeleton represents a significant class of biologically active nitrogen compounds that are found in various natural products and drugs with well-recognized pharmacological properties. In this personal account, we will briefly discuss the synthesis of allylamine skeletons. We will focus on showing a general protocol for Lewis acid-catalyzed N-allylation of electron-poor N-heterocyclic amides and sulfonamide via an amide-aldehyde-alkene condensation reaction. The substrate scope with respect to N-heterocyclic amides, aldehydes, and alkenes will be discussed. This method is also capable of preparing the Naftifine motif from N-methyl-1-naphthamide or methyl (naphthalene-1-ylmethyl)carbamate, with paraformaldehyde and styrene in a one-pot manner.

Catalyst-free Biginelli-type synthesis of new functionalized 4,7-dihydropyrazolo[1,5-a]pyrimidines

New pyrazolopyrimidines and pyrazoloquinazolines were synthesized through the uncatalyzed reaction of 5-amino-3-arylpyrazole-4-carbonitriles with aldehydes and 1,3-dicarbonyl compounds.

Synthesis of N-alkyl (aril)-tetra pyrimidine thiones and investigation of their human carbonic anhydrase I and II inhibitory effects

Tetrahydropyrimidine thiones, which are cyclic thiocarbamides derivatives, were synthesised from thiourea, β-diketones and substituted benzaldehydes. A tautomeric form of these derivatives incorporates the thiol functionality, which is known to interact with metal ions from metalloenzymes active sites, such as the carbonic anhydrases (CAs, EC 4.2.1.1) among others. This is a superfamily of widespread enzymes, which catalyses a crucial biochemical reaction, the reversible hydration of carbon dioxide to bicarbonate and protons (H(+)). The newly synthesised N-alkyl (aril)-tetrahydropyrimidine thiones were tested for inhibition of the cytosolic human isoforms I and II (hCA I and II). Both isoforms were effectively inhibited by the newly synthesised thiones. Ki values were in the range of 218.5 ± 23.9-261.0 ± 41.5 pM for hCA I, and of 181.8 ± 41.9-273.6 ± 41.4 pM for hCA II, respectively. This under-investigated class of derivatives may bring interesting insights in the field of non-sulphonamide CA inhibitors.

4-Aryl-Pyrimidin-2-Yl Tosylates as Efficient Reaction Partners: Application to the Synthesis of Pyrimidines Functionalised with Propargyloxy and 1,2,3-Triazolo Groups

The 4-arylated pyrimidin-2-yl tosylate derivatives, easily prepared from cheap commercial materials, reacted efficiently with propargyl alcohol/NaOBut to give the corresponding 4-arylated 2-propargyloxy-pyrimidine derivatives which, in a one-pot reaction catalysed by CuSO4·5H2O/sodium ascorbate, reacted with NaN3 and hexyl or benzyl bromide to give a series of 2-(1-hexyl- or 1-benzyl-1,2,3-triazol-4-yl)methoxy-pyrimidine derivatives in good yields.

Poly(N-bromo-N-ethyl-benzene-1,3-disulfonamide) and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide as new efficient reagents for one-pot synthesis of furano and pyrano pyrimidinones (thiones)

We have developed an efficient procedure for the synthesis of furano and pyrano pyrimidinones (thiones) using PBBS and TBBDA as new reagents.

Modified multicomponent Biginelli–Atwal reaction towards a straightforward construction of 5,6-dihydropyrimidin-4-ones

A modified multicomponent Biginelli condensation with Meldrum's acid affords a straightforward access to 5,6-dihydropyrimidin-4-ones through a domino Knoevenagel-aza-Michael-Cyclocondensation (KaMC) reaction.

Selective reduction of nitro-compounds to primary amines by nickel-catalyzed hydrosilylative reduction

The tolerances of many functional groups, e.g. aryl-chloride, aryl-bromide, alkene, alkynyl, ester, ether, oxhydryl, carboxylic acid, cyano group, nitrine, carbonyl, acyl, thioether and some heterocycles, were studied with unprecedentedly high chemoselectivity.

Fe3O4–CNTs nanocomposites: a novel and excellent catalyst in the synthesis of diarylpyrimidinones using grindstone chemistry

The Fe₃O₄–CNTs in conjunction with grindstone chemistry have been used in this report to synthesize 5-unsubstituted pyrimidinones.

Three Component Reaction: An Efficient Synthesis and Reactions of 3,4-Dihydropyrimidin-2(1H)-Ones and Thiones Using New Natural Catalyst

Synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives from aldehydes, 1,3-dicarbonyl derivatives and urea or thiourea using granite and quartz as new, natural and reusable catalysts. Some of the 3,4-dihydropyrimidin-2(1H)-thione derivatives were used to prepare new heterocyclic compounds. The antimicrobial activity of selected examples of the synthesized compounds was tested and showed moderate activity.