Efficient C-S and C-N cross-coupling reactions have been developed for regioselective, scalable and environmentally benign synthesis of substituted phenothiazine derivatives. Cross-coupling reactions were demonstrated on various challenging substrates using non-toxic, highly economical, readily available ferric citrate as a catalyst to get desired product with high regioselectivity. Atom economy is the added advantage of this protocol since additional N-protection step before coupling and eventual deprotection of the same to obtain the desired product arenot required. To the best of our knowledge, this is the first report on the use of inexpensive ferric citrate as a catalyst without involving any ligand for the synthesis of regioselectively substituted phenothiazine.

Melting points are taken on a precision melting point apparatus (DBK) instrument and are uncorrected. IR spectra are obtained in potassium bromide (KBr) disks on a Bruker IR Spectrometer and H 1 NMR spectra were obtained on deuteriodimethylsulfoxide (DMSO-d6) as well as CDCl 3 on a 400 MHz spectrometer. GC (VARIAN CP-3800 GC, HP-5 capillary column, FID detector), Mass spectra were recorded on a MicroMass spectrometer by Waters. All starting materials purchased from commercial source. Substrate (2s to 2w) was synthesised following reported process. [1] Raw materials procured from spectrochem.2 General procedure for synthesis of compounds 3a-3ao.4 mmol of carboxylic acid in toluene (5 vol) was added with sodium borohydride(2.5 mmol) in portions at 0-5°C. To the mixture was added EnCat Ni 2.5%.Gradually raise the temperature to 25-30°C. To the mixture was added 1 mmol secondary amine. Raise the temperature to 80°C. To the reaction mixture was added 1.5 mmol of sodiumborohydride in portions. The progress of the reaction was monitored by TLC. After the completion of reaction, reaction mixture was quenched with 1N HCl to pH 7 to 8 and separated organic solution washed with water. Solvent was distilled out under reduce pressure at 50°C. The product was isolated by crystallisation in isopropyl alcohol and conc. Hydrochloric acid followed by filtration and drying to yield (90-99%) solid hydrochloride salt as product.3 Characterisation Data. 4-(benzo[d]thiazol-2-yl(methyl)amino)-2-fluoro-N-methylbenzamide (3x); White

An environmentally benign, efficient and scalable approach for the synthesis of 3,4‐dihydropyrimidin‐(1H)‐ones (DHPMs) is reported. The multi component one‐pot reaction is catalysed by either itaconic acid or its salt, which are non‐hazardous, readily available, mild and biodegradable with a simple workup procedure. To the best of our knowledge, this is the first report on the use of itaconic acid as a catalyst in organic transformation. Diverse and new challenging DHPMs have been synthesized using this methodology in excellent yields and in addition the practicality of the method is demonstrated on multi gram level.

In the present report, inter and intramolecular C−N bond formation between the carbonyl carbon of urea or amide functional group with various amines mediated by triflic anhydride and 2‐nitropyridine is successfully investigated for the first time. The versatility of the method is demonstrated by exploring it on a wide range of substrates to synthesize diversified 2‐aminobenzimidazole, 2‐aminopyridoimidazole and 2‐substituted benzimidazole and benzthiazoles. Short reaction time, high yields and applicability in milder metal free reaction conditions are the highlights of the present methodology.