Chemistry of 2-(Piperazin-1-yl) quinoline-3-Carbaldehydes

: This review described the preparation of 2- chloroquinoline-3-carbaldehyde derivatives 18 through Vilsmeier-Haack formylation of N-arylacetamides and use of them as a key intermediate for preparation of 2-(piperazin-1-yl) quinoline-3-carbaldehydes. The synthesis of the 2-(piperazin-1-yl) quinolines derivatives was explained through the following chemical reactions: acylation, sulfonylation, Claisen-Schmidt condensation, 1, 3-dipolar cycloaddition, one-pot multicomponent reactions (MCRs), reductive amination, Grignard reaction and Kabachnik-Field’s reaction.

Multistep batch-flow hybrid synthesis of a terbinafine precursor

A three-step batch-flow hybrid process has been developed for an expeditious synthesis of the enynol key intermediate of antifungal terbinafine. This procedure involves consecutive organometallic steps without the necessity of any in-line purification: after a metalation by n-butyllithium, a selective addition of the lithium salt was elaborated followed by a Grignard reaction resulting in a high yield of 6,6-dimethylhept-1-en-4-yn-3-ol. Moreover, as an alternative to tetrahydrofuran, cyclopentyl methyl ether was used as solvent implementing a safe, sustainable, yet selective synthetic process. Even on a laboratory-scale, the optimized batch-flow hybrid process had a theoretical throughput of 41 g/h. Furthermore, the newly developed process provides an efficient synthesis route to the key-intermediate, while making acrolein obsolete, minimizing side-products, and enabling safe and convenient scale-up.

Design, Synthesis and Antibacterial Activity of N-(3-((4-(6-(2,2,2- Trifluoroethoxy)pyridin-3-yl)-1H-imidazol-2-yl)methyl)oxetan-3-yl)amide Derivatives

A new series of N-(3-((4-(6-(2,2,2-trifluoroethoxy)pyridin-3-yl)-1H-imidazol-2-yl)methyl)oxetan-3- yl)amide derivatives (10a-h)were synthesized by the reaction of 3-((4-(6-(2,2,2-trifluoroethoxy)pyridin- 3-yl)-1H-imidazol-2-yl)methyl)oxetan-3-amine (8) with various carboxylic acids in the presence of T3P catalyst. The reaction is usually furnished within 60 min with good isolated yields. Coupling of 6-(2,2,2-trifluoroethoxy) nicotinic acid (1) with Weinreb amine hydrochloride gave N-methoxy-Nmethyl- 6-(2,2,2-trifluoroethoxy) nicotinamide (2). Compound 3 was synthesized by the Grignard reaction of compound 2 with methylmagnesium bromide. Bromination of compound 3 with N-bromo succinamide to obtain 2-bromo-1-(6-(2,2,2-trifluoroethoxy)pyridin-3-yl)ethan-1-one (4), which was reacted with 2-(3-(((benzyloxy)carbonyl)amino)oxetan-3-yl)acetic acid (5) gave 2-oxo-2-(6-(2,2,2- trifluoroethoxy)pyridin-3-yl)ethyl 2-(3-(((benzyloxy)carbonyl)amino)oxetan-3-yl)acetate (6). Compound 7 was synthesized by the cyclization of compound 6 with ammonium acetate. Finally, debenzylation of compound 7 gave 3-((4-(6-(2,2,2-trifluoroethoxy)pyridin-3-yl)-1H-imidazol-2- yl)methyl)oxetan-3-amine (8). All the synthesized amide compounds were characterized by analytical spectral techniques, like 1H & 13C NMR and LCMS and also evaluated their antibacterial activity.

Synthesis of a Homologous Series of Trialkyl Arsines (C3-C12) and Applications of Arsenic Triiodide as a Synthetic Precursor

This work presents some modifications in the post-synthetic processing for a classical arsenic reagent: AsI3. In comparison with the widely used analog, the trichloride, arsenic triiodide presents several advantages such as low toxicity, air stability, and low volatility. It was used as a synthetic precursor in the preparation of a variety of arsenic(III) derivatives like arsines, arsenites, and thioarsenites. Besides that, AsI3 was submitted to a diversity-oriented Grignard reaction in the preparation of a homologous series of trialkyl arsines ranging from AsC3H9 to AsC12H27. The series was analyzed by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry to provide a trialkyl arsines library that can be used for the direct analysis of natural samples.

Empowering alcohols as carbonyl surrogates for Grignard-type reactions

The Grignard reaction is a fundamental tool for constructing C-C bonds. Although it is widely used in synthetic chemistry, it is normally applied in early stage functionalizations owing to poor functional group tolerance and less availability of carbonyls at late stages of molecular modifications. Herein, we report a Grignard-type reaction with alcohols as carbonyl surrogates by using a ruthenium(II) PNP-pincer complex as catalyst. This transformation proceeds via a carbonyl intermediate generated in situ from the dehydrogenation of alcohols, which is followed by a Grignard-type reaction with a hydrazone carbanion to form a C-C bond. The reaction conditions are mild and can tolerate a broad range of substrates. Moreover, no oxidant is involved during the entire transformation, with only H2 and N2 being generated as byproducts. This reaction opens up a new avenue for Grignard-type reactions by enabling the use of naturally abundant alcohols as starting materials without the need for pre-synthesizing carbonyls.

Synthesis of Spiro[cycloalkane-pyridazinones] with High Fsp3 Character Part 2.*

An extended compound library of spiro[cycloalkane-pyridazinones] with high Fsp3 character is targeted. There are two possibilities to improve the physicochemical parameters of a drug candidate molecules or building blocks, either to replace the aromatic systems with bioisoster heteroaromatic moieties, e.g. with one or two nitrogen containing ring systems (pyridines, pyridazines, pyrimidines, etc.), or to increase the Fsp3 character of the compounds. Using a new synthetic ap-proach, the Grignard reaction of 2-oxaspiro[4,5]decane-1,3-dione and 2-oxaspiro[4,4]nonane-1,3-dione with p-halophenyl- or p-alkylphenyl-magnesium bromide resulted in the formation of the corresponding 2-oxoethyl-cycloalkanecarboxylic ac-ids, which served as starting materials for the formation of pyridazinone with hydrazine or phenylhydrazine. The pyridazi-nones obtained were alkylated with methyliodide or benzylbromide. 16 Novel 4-tolyl- or 4-halophenyl-2,3-diazaspiro[5.5]undec-3-en-1-one and 4-tolyl- or 4-halopyhenyl-7,8-diazaspiro[4.5]dec-8-en-6-one, and their N-methyl, N-benzyl, and N-phenyl derivatives were synthetized.The physicochemical parameters and the Fsp3 character of the novel compounds obtained were studied. A few of them showed excellent logP and clogP values, but introduction of further phe-nyl group seemed to be disadvantageous