Oxidative Nickel-Catalyzed ortho-C-H Amination of (Iso)quinolines with Alicyclic Amines Directed by a Sacrificial N-Oxide Group.

Transition metal (TM)-catalyzed direct amination of C-H bonds on free or fused pyridine (Py) rings with free amines still remains scarce because amines and the Py ring tend to adopt a nonproductive N-bound coordination with many TMs, leading to a significant decrease of catalytic reactivity. We herein disclose a nickel-catalyzed and a sacrificial N-oxide group directed oxidative coupling of (iso)quinolyl C-H bonds and alicyclic amines, which furnishes bioimportant amino(iso)quinolines efficiently and selectively in a single step. Noteworthy, this protocol avoids the use of aggressive reactants and very strong bases usually required when aminating on nonoxidized Py rings.

An improved multi-strategy beluga whale optimization for global optimization problems.

This paper presents an improved beluga whale optimization (IBWO) algorithm, which is mainly used to solve global optimization problems and engineering problems. This improvement is proposed to solve the imbalance between exploration and exploitation and to solve the problem of insufficient convergence accuracy and speed of beluga whale optimization (BWO). In IBWO, we use a new group action strategy (GAS), which replaces the exploration phase in BWO. It was inspired by the group hunting behavior of beluga whales in nature. The GAS keeps individual belugas whales together, allowing them to hide together from the threat posed by their natural enemy, the tiger shark. It also enables the exchange of location information between individual belugas whales to enhance the balance between local and global lookups. On this basis, the dynamic pinhole imaging strategy (DPIS) and quadratic interpolation strategy (QIS) are added to improve the global optimization ability and search rate of IBWO and maintain diversity. In a comparison experiment, the performance of the optimization algorithm (IBWO) was tested by using CEC2017 and CEC2020 benchmark functions of different dimensions. Performance was analyzed by observing experimental data, convergence curves, and box graphs, and the results were tested using the Wilcoxon rank sum test. The results show that IBWO has good optimization performance and robustness. Finally, the applicability of IBWO to practical engineering problems is verified by five engineering problems.

Modified reptile search algorithm with multi-hunting coordination strategy for global optimization problems.

The reptile search algorithm (RSA) is a bionic algorithm proposed by Abualigah. et al. in 2020. RSA simulates the whole process of crocodiles encircling and catching prey. Specifically, the encircling stage includes high walking and belly walking, and the hunting stage includes hunting coordination and cooperation. However, in the middle and later stages of the iteration, most search agents will move towards the optimal solution. However, if the optimal solution falls into local optimum, the population will fall into stagnation. Therefore, RSA cannot converge when solving complex problems. To enable RSA to solve more problems, this paper proposes a multi-hunting coordination strategy by combining Lagrange interpolation and teaching-learning-based optimization (TLBO) algorithm's student stage. Multi-hunting cooperation strategy will make multiple search agents coordinate with each other. Compared with the hunting cooperation strategy in the original RSA, the multi-hunting cooperation strategy has been greatly improved RSA's global capability. Moreover, considering RSA's weak ability to jump out of the local optimum in the middle and later stages, this paper adds the Lens pposition-based learning (LOBL) and restart strategy. Based on the above strategy, a modified reptile search algorithm with a multi-hunting coordination strategy (MRSA) is proposed. To verify the above strategies' effectiveness for RSA, 23 benchmark and CEC2020 functions were used to test MRSA's performance. In addition, MRSA's solutions to six engineering problems reflected MRSA's engineering applicability. It can be seen from the experiment that MRSA has better performance in solving test functions and engineering problems.

Selective Phosphoranation of Unactivated Alkynes with Phosphonium Cation To Achieve Isoquinoline Synthesis.

We herein develop a selective phosphoranation of alkynes with phosphonium cation, which directs a concise approach to isoquinolines from unactivated alkyne and nitrile feedstocks in a single step. Mechanistic studies suggest that the annulation reaction is initiated by the unprecedented phosphoranation of alkynes, thus representing a unique reaction pattern of phosphonium salts and distinguishing it from existing protocols that largely rely on the utilization of highly functionalized imines/oximes and/or highly polarized alkynes.

Formation of Methylene Linkage for N-Heterocycles: Sequential C-H and C-O Bond Functionalization of Methanol with Cosolvent Water.

An iron-catalyzed methylene forming strategy is disclosed through sequential C-H and C-O bond functionalization of methanol with cosolvent water. This protocol provides an easy and novel access to methylene-tethered imidazo[1,2- a]pyridine and 2-aminopyridine analogues in a sustainable manner and represents a complementary approach to traditional methylene forming strategies.

Copper-Catalyzed Dehydrogenative C(sp2)-N Bond Formation via Direct Oxidative Activation of an Anilidic N-H Bond: Synthesis of Benzoimidazo[1,2-a]indoles.

A dehydrogenative C(sp2)-N bond-forming strategy via copper-catalyzed intramolecular C-H/N-H coupling has been developed, which systematically unraveled the feasibility and practicality for benzoimdazo[1,2-a]indole formations through oxidative anilidic N-H activation. The merit of this strategy is illustrated by the broad tolerance of functionalities, as well as the utilization of extremely cheap copper catalysis to realize potentially useful indole-fused tetracycles in a step- and atom-economical manner.

Iron-Catalyzed Dehydrogenative sp3-sp2 Coupling via Direct Oxidative C-H Activation of Acetonitrile.

An iron-catalyzed dehydrogenative sp3-sp2 coupling of acetonitrile and 2-arylimidazo[1,2-a]pyridine has been realized, which can serve as a novel approach toward heteroarylacetonitriles. The merit of this strategy is illustrated by the breadth of functional groups tolerated in the transformation and the fast access to pharmaceuticals (such as zolpidem) directly from the heteroarylacetonitriles.

Ruthenium-catalyzed aldehyde functionality reshuffle: selective synthesis of E-2-arylcinnamaldehydes from E-ß-bromostyrenes and aryl aldehydes.

A new concept for highly selective synthesis of E-2-arylcinnamaldehydes has been developed via a formal arylformylation of E-ß-bromostyrenes with readily available aryl aldehydes. This strategy involves an overall reshuffle of the aldehyde functionality with a loss of hydrogen bromide.

Rhodium-catalyzed xanthone formation from 2-aryloxybenzaldehydes via cross-dehydrogenative coupling (CDC).

A concise and straightforward strategy to construct a xanthone skeleton via an intramolecular cross-dehydrogenative coupling (CDC) of 2-aryloxybenzaldehydes has been developed. The reaction proceeded smoothly without any need of preactivation of the aldehyde group. It can tolerate various functional groups and provides an applicable protocol to construct a wide range of xanthone derivatives.

Highly(≥98%) Stereo- and Regioselective Trisubstituted Alkene Synthesis of Wide Applicability via 1-Halo-1-alkyne Hydroboration-Tandem Negishi-Suzuki Coupling or Organoborate Migratory Insertion Protocol.

(Z)-1-Halo-1-alkenylboranes (7), preparable in 82-90% yields as ≥98% isomerically pure compounds via hydroboration of 1-halo-1-alkynes, have been converted to a wide range of trisubstituted alkenes via three different routes in the tail-to-head (T-to-H) direction, i.e., (i) Palladium-catalyzed Negishi-Suzuki tandem alkenylation, (ii) treatment of 7 with organolithium or Grignard reagents to generate α-bromo-1-alkenylboronate complexes (10) that can undergo migratory insertion of a carbon group (R2) to form (E)-alkenylboranes (11) with inversion of alkene configuration (≥98% inversion), followed by fluoride-promoted Suzuki alkenylation, and (iii) Negishi coupling to generate (Z)-alkenylboranes (8) in ≥98% retention of configuration, followed by treatment with organolithium or Grignard reagents to produce trisubstituted alkenes with reversed stereo configurations. The synthetic utility of the present methodology has been demonstrated in the highly selective synthesis of side chain (4) of scyphostatin in 28% yield over nine steps in the longest linear sequence from allyl alcohol. Thus, this new tandem protocol has been emerged as the most widely applicable and highly selective route to trisubstituted alkenes including those that are otherwise difficult to prepare.

Alkyne elementometalation-Pd-catalyzed cross-coupling. Toward synthesis of all conceivable types of acyclic alkenes in high yields, efficiently, selectively, economically, and safely: "green" way.

Palladium-catalyzed cross-coupling reactions, especially those involving Zn, Al, Zr (Negishi coupling), and B (Suzuki coupling), collectively have brought about "revolutionary" changes in organic synthesis. Thus, two regio- and stereodefined carbon groups generated as R(1)M (M = Zn, Al, B, Cu, Zr, etc.) and R(2)X (X = I, Br, OTs, etc.) may now be cross-coupled to give R(1)-R(2) with essentially full retention of all structural features. For alkene syntheses, alkyne elementometalation reactions including hydrometalation (B, Al, Zr, etc.), carbometalation (Cu, Al-Zr, etc.), and haloboration (BX(3) where X is Cl, Br, and I) have proven to be critically important. Some representative examples of highly efficient and selective (>or=98%) syntheses of di-, tri-, and oligoenes containing regio- and stereodefined di- and trisubstituted alkenes of all conceivable types will be discussed with emphasis on those of natural products. Some interesting but undesirable cases involving loss of the initial structural identities of the alkenyl groups are attributable to the formation of allylpalladium species, which must be either tamed or avoided. Some such examples involving the synthesis of 1,3-, 1,4-, and 1,5-dienes will also be discussed.

Highly(≥98%) Selective Trisubstituted Alkene Synthesis of Wide Applicability via Fluoride-Promoted Pd-Catalyzed Cross-Coupling of Alkenylboranes.

(Z)-ß-bromo-1-propenyl(pinacol)borane(4), recently made available in 85% yield as a ≥98% isomerically pure compound via bromoboration of 1-propyne, has been converted to ß-alkyl-, aryl-, and alkenyl-substituted (Z)-2-methyl-1-alkenyl(pinacol)boranes(2a) in ca. 75% yield based on propyne via Pd-catalyzed Negishi alkenylation with suitable organozinc bromide. The previously sluggish and modest-yielding Suzuki alkenylation of ß,ß-disubstituted alkenylboranes has been significantly promoted by fluorides, especially nBu4NF(TBAF) or CsF to give trisubstituted alkenes, i.e., (Z)-ß-Me-substituted 3-i-3-xi and (E)-ß-Ph-substituted 2b-i and 2b-ii. In all cases, each alkene product was formed in a ≥98% seteoselectivity. The propyne-based protocol nicely complements the widely used Zr-catalyzed alkyne methylalumination-Pd-catalyzed alkenylation by providing a highly stereoselective(≥98%) route to (Z)-Me-substituted alkenes.

A versatile and efficient ligand for copper-catalyzed formation of C-N, C-O, and P-C bonds: pyrrolidine-2-phosphonic acid phenyl monoester.

A new and readily available bidentate ligand, namely, pyrrolidine-2-phosphonic acid phenyl monoester (PPAPM), has been developed for the copper-catalyzed formation of C-N, C-O, and P-C bonds, and various N-, O-, and P-arylation products were synthesized in good to excellent yields by using the CuI/PPAPM catalyst system. Addition of the PPAPM ligand greatly increases the reactivity of the copper catalyst, and the resulting versatile and efficient catalyst system is of widespread and practical application in cross-coupling reactions.

Copper-catalyzed arylation of amines using diphenyl pyrrolidine-2-phosphonate as the new ligand.

[Chemical reaction: See text] We have developed a general, efficient, and inexpensive catalyst system for arylation of amines by using 10 mol % of CuI as the copper source, 20 mol % of diphenyl pyrrolidine-2-phosphonate (DPP) as the ligand, K3PO4 as the base, and DMF containing 2% water (v/v) as the solvent.