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Organic transformations using visible light‐mediated photoredox reactions received significant attention in the past several years. Recently, nitroalkenes have emerged as an excellent coupling partner in the visible light‐mediated photoredox reactions. Due to the easy availability and diverse reactivity, several methodologies are reported on the photoredox‐mediated reactions of nitroalkenes to attain different types of alkenes and heterocycles. Variety of reactions including denitrative coupling reactions, addition reactions and cycloadditions, etc. are reported. However, a review that focuses entirely on this topic has not appeared yet. Considering the synthetic potential of these class of reactions, we provide a summary of various methodologies developed for the reactions of nitroalkenes under visible light photoredox catalysis. [ABSTRACT FROM AUTHOR]

A mild and metal‐free method for the one‐pot synthesis of highly substituted tetrahydro‐α‐carbolines from Morita‐Baylis‐Hillman (MBH) bromides of nitroalkenes and iminoindolines has been demonstrated. Cascade reaction of MBH bromides with tosyliminoindolines occurs with regio‐ as well as diastereoselectivity in a formal [3+3] manner to form various tetrahydro‐α‐carbolines with wide substrate scope under mild conditions. All the products were obtained in high yields within a short reaction time. Also, the synthetic efficiency of the methodology was demonstrated by a gram scale experiment and by further converting them into 3‐nitro‐α‐carbolines. [ABSTRACT FROM AUTHOR]

Due to the high reactivity of cyclopropanes, different methods have been developed for their stereo‐ and regio‐controlled ring‐opening reactions to achieve a variety of synthetically useful targets. The traditional methods for the ring‐opening include thermolysis, use of oxidants, transition metals or radical precursors in which many of them encounter various difficulties. In the past several years, visible‐light‐mediated photoredox reactions received considerable attention for various organic transformations. Several methodologies have been developed in recent times for the visible‐light‐mediated ring‐opening reactions of cyclopropanes. Considering the synthetic potential of this class of reactions, we provide a summary of various methodologies developed for the cyclopropane ring‐opening reactions under visible‐light photoredox catalysis. [ABSTRACT FROM AUTHOR]

As a naturally occurring small‐molecule, various optical isomers of chiral pyrrolo[2,1‐a]isoquinoline alkaloid crispine A represent a potential class of chiral molecules in contemporary organic chemistry, and possess diverse biological activities. The range of pharmacological activities include antidepressant, antiplatelet, antileukemic, and anticancer activities. This review provides an overview of the literature on the strategies, employed in the synthesis of crispine A in their racemic and enantiopure forms via Bischler‐Napieralski cyclization, Pictet‐Spengler cyclization, N‐Alkylation/Acylation‐cyclization, Oxidative cyclization, and Asymmetric hydrogenation in the period of 1931–2021. This study accentuates the need for the developing more effective synthesis, and search for involved biological applications for the pyrroloisoquinoline class of natural product. Attention has been drawn towards the use of relatively less documented but easily accessible naturally occurring diastereomeric scaffolds namely, garcinia and hibiscus acids. These lactones obtained from (+)‐ and (−)‐2‐hydroxycitric acids bearing chemically amenable functional groups are investigated as an ideal choice for the enantiopure synthesis of the (−)‐(R)‐ and (+)‐(S)‐Crispine A structural frame work. [ABSTRACT FROM AUTHOR]

The development of palladium-catalyzed α-arylation of carbonyl compounds has emerged as a new avenue in the design of new routes for the synthesis of natural products and active pharmaceutical ingredients (APIs). In many cases, syntheses based on α-arylation strategies provide elegant routes in terms of increasing the overall yields, improving the synthesis scope, and decreasing the number of steps. This microreview aims to highlight the importance of palladium-catalyzed α-arylation methodologies, covering a range of notable reported examples of the total syntheses of structurally important compounds, thereby highlighting the importance of this powerful methodology for key steps in organic synthesis. [ABSTRACT FROM AUTHOR]

Cover Feature: Synthesis of Pyrrolo[2,1-a]isoquinoline Class of Natural Product Crispine A (Eur. J. Org. Keywords: Alkaloids; Crispine A; Natural product; Pyrrolo[2,1-a]isoquinoline; Synthetic Methods; Total synthesis EN Alkaloids Crispine A Natural product Pyrrolo[2,1-a]isoquinoline Synthetic Methods Total synthesis 4896 4896 1 09/29/21 20210921 NES 210921 B The Cover Feature b shows naturally occurring (2 I S i ,3 I S i )- and (2 I S i ,3 I R i )-tetrahydro-3-hydroxy-5-oxo-2,3-furan dicarboxylic acid bearing, chemically amenable functional groups that are an ideal choice for the enantiopure synthesis of the (-)- and (+)-Crispine A, respectively. Alkaloids, Crispine A, Natural product, Pyrrolo[2,1-a]isoquinoline, Synthetic Methods, Total synthesis. [Extracted from the article]

Review: [recent applications of α-arylation in total syntheses both of natural products and of active pharmaceutical ingredients; 80 refs. [ABSTRACT FROM AUTHOR]

A facile, metal-free method for the synthesis of substituted α-carbolines from secondary Morita-Baylis-Hillman (MBH) acetates of nitroalkenes is presented. The cascade reaction of MBH acetates with tosyliminoindolines occurs regioselectively to form various α-carbolines with a wide substrate scope. The reaction involves mild conditions, and the products are formed in high yields within a short reaction time. The amenability of the reaction to scale up and synthetic applications of the products have been demonstrated.