Schwannomas are benign tumours that arise from the Schwann cells of nerve fibres. They commonly occur in the head and neck, mediastinum and extremities. They are extremely rare in the pelvis. These are usually slow growing tumours and are often detected incidentally. Pre-operative diagnosis is extremely difficult as there are no definitive signs on imaging. Aspiration biopsy is often inconclusive or misleading. Surgical excision is both diagnostic and therapeutic. As these tumours are often large in size, open excision is most commonly performed. We describe a case of a large, cystic schwannoma of the pelvis causing bladder outlet obstruction and bilateral hydroureteronephrosis. Complete surgical excision was performed laparoscopically.

Herein, we report azo-benzimidazole containing cobalt complexes (1−3) for alcohol dehydrogenation-triggered C3-alkylation of indoles. In complexes 1−3, ligands are redox noninnocent and showed facile irreversible L/L • reduction followed by Co(II)/Co(I) reduction in close-lying potentials. Taking advantage of facile redox events in 1−3, the first aerial dehydrogenation of alcohols to their corresponding carbonyl compounds is explored. Subsequently, C3-alkylation of indole was studied using alcohols as the alkylating agents. The developed catalytic protocol was found to be efficient and very selective. It has a broad substrate scope and good functional group tolerance. As far as we are aware, it is the first homogeneous cobalt catalyst for C3-alkylation of indole using alcohol as the alkylating agent. Detailed mechanistic studies, including a deuterium labeling experiment, have suggested a borrowing hydrogen method for the C3-alkylation of indole. The coordinated ligand, cooperatively with the Co(II)/Co(I) redox couple, oxidized the coordinated alkoxide in a radical pathway to result in the carbonyl compound (Scheme 1), which on subsequent condensation with indole generates the alkylideneindolenine intermediate "X". Reduction of "X" by an azo-anion radical Co(I) catalyst intermediate resulted in the C3-alkylated indole.

A series of azo-aromatic copper(II) complexes, [1ag] and a Cu(I) complex, [1h], with varying amine-functionalized hemilabile pincer-like [HL 1−3 ] and [L 1,2 ], methyl-substituted azo [L 3 ], and imine [L 4 ] ligands, were synthesized and characterized. These complexes were investigated for aerobic oxidation of a variety of aromatic alcohols in the presence of 2.0 mol % precatalysts [1a-g], cobaltocene (2.0 mol %), N-methyl imidazole (NMI) (8.0 mol %), and TEMPOH (2.0 mol %) at room temperature. The Cu(I) complex (1h) acted as a catalyst in the absence of cobaltocene. To understand the mechanism, detailed experimental and theoretical studies have been performed with the representative complex [1a], which has suggested a new kind of mechanism involving a Cu(II)/Cu(I) redox couple. Cobaltocene acts as a reductant to [1a] to generate a Cu(I) complex, which activates dioxygen in the presence of NMI. TEMPOH transfers a hydrogen atom to the activated dioxygen with the generation of TEMPO•, which further participates in α-C−H bond activation in the Cu(II)-alkoxide intermediate in an intermolecular fashion in the catalytic cycle. The amine sidearm in the ligand backbone of the complexes has a significant role in catalytic activity. Complexes with amine sidearms are more effective than complexes without them. Moreover, the aliphatic secondary amine sidearm is more efficient among the amine sidearm than the aromatic secondary amine and tertiary amines. The amine sidearm that remained coordinated to the Cu(II) center is hemilabile, and it facilitates alcohol coordination in the catalytic process. Alcohol coordination was the rate-limiting step, and it was supported by the isotope effect study on benzyl alcohol, substitution effect on the amine moiety of the ligands, and DFT calculation. The hemilabile amine sidearm of the coordinated ligand also acted as a base in deprotonating the alcoholic O−H proton and acted as an acid in releasing H 2 O 2 during the catalysis.

A series of Cu(II) complexes, 1−4 and 6, were synthesized through a reaction of amine-functionalized pincer-like ligands, HL 1,2 , L a,b , and a bidentate ligand L 1 with CuCl 2 •2H 2 O. The chemical reduction of complex 1 using 1 equiv of sodium Lascorbate resulted in a dimeric Cu(I) complex 5 in excellent yield. All of the complexes, 1−6, were thoroughly characterized using various physicochemical characterization techniques, single-crystal X-ray structure determination, and density functional theory calculations. Ligands HL 1,2 and L a,b behaved as tridentated donors by the coordination of the amine side arm in their respective Cu(II) complexes, and the amine side arm remained as a pendant in Cu(I) complexes. All of these complexes (1−6) were explored for copper(I)-catalyzed 1,3-dipolar azide−alkyne cycloaddition (CuAAC) reaction at room temperature in water under air. Complex 5 directly served as an active catalyst; however, complexes 1−4 and 6 required 1 equiv of sodium L-ascorbate to generate their corresponding active Cu(I) catalyst. It has been observed that azobased ligand-containing Cu(I)-complexes are air-stable and were highly efficient for the CuAAC reaction. The amine side arm in the ligand backbone has a dramatic role in accelerating the reaction rate. Mechanistic investigations showed that the alkyne C−H deprotonation was the rate-limiting step and the pendant amine side arm intramolecularly served as a base for Cu-coordinated alkyne deprotonation, leading to the azide−alkyne 2 + 3 cycloaddition reaction. Thus, variation of the amine side arm in complexes 1−4 and use of the most basic diisopropyl amine moiety in complex 4 has resulted in an unique amine-functionalized azoaromatic Cu(I) system for CuAAC reaction upon sodium L-ascorbate reduction. The complex 4 has shown excellent catalysis at its low partsper-million level loading in water. The catalytic protocol was versatile and exhibited very good functional group tolerance. It was also employed efficiently to synthesize a number of useful functional triazoles having medicinal, catalytic, and targeting properties.

A general electrophilic iodocyclization/nucleophile addition cascade transformation for 1,2-alkynediones for the synthesis of various oxygen heterocycles and access to regioselective alkyne hydroxylation is reported. Furan-tethered ynediones resulted in the construction of exo-enol ethers via carbonyl-alkyne cyclization-initiated heteroarene dearomatization, whereas other (hetero)arene-, alkenyl-, and alkyl-tethered ynediones resulted in the formation of highly functionalized 3(2H)-furanones. Importantly, the developed domino protocols involve the construction of important heterocyclic scaffolds and installation of two functional groups in a single operation. Moreover, the use of water as a nucleophile resulted in regioselective alkyne hydroxylation via furanone ring opening. The developed protocols are characterized by a wide substrate scope, and their utility has been demonstrated by a number of postsynthetic transformations.