Hydrogen-atom transfer (HAT) counts amongst the most widely investigated routes to carbon-centered radicals. Intramolecular processes involving 1,5-HAT are widespread to promote regioselective radical "CH activation". The aim of this review is to draw up a comprehensive inventory of the less commonly encountered 1,n-radical translocations (n≠5) with the aim to update this topic with the most recent relevant data.

Scheme 24 Enantioselective Radical Hydroacylation of Enals with α-Ketoacids byMerging Photoredox Catalysis with Amine Catalysis.Jang et al. exploited enantioselective tandem Michael addition/oxyamination of α,β-unsaturated aldehydes by combining asymmetric iminium catalysis using organocatalyst with photoinduced SOMO catalysis using N719/TiO2. 60 Here, TiO2 acts as a second cooperative photocatalyst along with Ru photocatalyst N719 which bound to the latter, increases the enantio-and diastereoselectivity of the process. Adamantane carboxylic acid (30 mol%) was used as an additive which promotes formation of iminium ion 2.1.48A from aldehyde 2.1.48 and chiral amine catalyst. This iminium intermediate then reacts with diethyl malonate to provide intermediate 2.1.48B which either undergoes hydrolysis to form β-substituted aldehyde 2.1.50 or photo-oxidation by the photoexcited Ru(II) dye to form enamine radical 2.1.48C. Subsequent addition of TEMPO to radical intermediate 2.1.48BC followed by hydrolysis afforded the desired product 2.1.49 (Scheme 25). This mechanism is obeying to a polar/radical crossover sequence where the first stereocontrol arises from the addition of the malonate.Recently, Bach group reported promising preliminary results of enantioselective [2+2] photocycloaddition of cinnamaldehyde in the presence of ruthenium photocatalyst and proline derived organocatalyst. 61

No abstract

No abstract

No abstract

Sultams are very important scaffolds both in medicinal chemistry and in synthetic organic chemistry. Very important methodologies for the asymmetric and non‐asymmetric synthesis of sultams, including asymmetric synthesis with memory of chirality (MOC), have recently been developed. Nowadays sultams are tremendously widely applied both in the medicinal field and in the synthetic field for the synthesis of different natural and non‐natural heterocycles. This review covers the recent development (2011–June 2017) of powerful methodologies for the synthesis of sultams and their applications in various fields during this period. A critical view of the mechanisms of the developed methodologies together with the scope and limitations of these methods add an extra dimension to the text.

No abstract

The present text discussed about the recent developments and applications of the Ullmann reaction in respect of the C-C bond formation. The major drawback of the Ullmann reaction, i.e., harsh reaction condition has recently been overcome with the development of various synthetic methodologies. Green synthetic methodologies such as metal-, ligand-, and additive free conditions, recyclable heterogenous catalysts, microwave-and ultrasoundassisted synthesis, etc. have got special importance in this field. This text lucidly describes all these recently developed synthetic methodologies which make the century old Ullmann reaction much efficient, effective, economical and attractive in the field of synthetic organic chemistry. Onsurface Ullmann coupling for the C-C bond formation, i.e., invoking C-C coupling reactions on a reactive surface has been discussed. All such developments of the Ullmann C-C coupling facilitate its application in the synthesis of bioactive heterocycles, drug-like molecules and natural products which has also been discussed in this text.