Organocatalytic Reductive Amination of the Chiral Formylcyclopropanes: Scope and Applications.

We developed a sustainable three-component reductive amination protocol for the chemoselective coupling of optically active functionally rich donor-acceptor carbonyl-cyclopropanes with various amines under 10 mol % of diphenyl phosphate in the presence of Hantzsch ester as a hydride source. The catalytic selective reductive C-N coupling has wide advantages like no epimerization, no ring opening, large substrate scope, generating only mono -alkylation products and simultaneously resulting in chiral cyclopropane-containing amines possessing many applications in the medicinal chemistry. In this article, we have shown the synthetic applications of reductive C-N coupling reaction to make chiral α-carbonyl-cyclopropane containing amines , double C-N coupled cyclopropane-amines , unusual C-N/C-C coupled cyclopropane-amines , chiral -butylsulfinamide containing cyclopropanes , and functionally rich chiral cyclopropane-fused -heterocycles .

Catalytic Asymmetric Synthesis of Benzobicyclo[3.2.1]octanes.

Lawsone aldehydes were directly transformed into the biologically important, unique carbon skeleton of chiral methanobenzo[f]azulenes/methanodibenzo[a,d][7]annulenes in high dr and ee and in very good yields by using quinine-thiourea-catalyzed tandem Wittig/intramolecular Michael/intramolecular aldol reactions. This asymmetric catalytic tandem protocol will be highly useful because these final molecules are basic skeletons of important antibiotics.

Organocatalytic Formal Intramolecular [3+2]-Cycloaddition to Acquire Biologically Important Methanodibenzo[a,f]azulenes and Methanobenzo[f]azulenes.

Lawsones were transformed into the functionally rich framework of methanodibenzo[a,f]azulenes and methanobenzo[f]azulenes in a single- or two-pot operation through five organocatalytic sequential reactions in very good yields with excellent selectivities. These resultant molecules are basic skeletons of important antibiotics, which highlights the value of this formal intramolecular [3+2]-cycloaddition as a key protocol.

Modular Access to Chiral 2,3-Dihydrofurans and 3,4-Dihydro-2 H-pyrans by Stereospecific Activation of Formylcyclopropanes through Combination of Organocatalytic Reductive Coupling and Lewis-Acid-Catalyzed Annulative Ring-Opening Reactions.

An organocatalytic reductive coupling and Lewis-acid-catalyzed annulative ring-opening strategy is developed as a two-step protocol for the stereoselective synthesis of dihydropyrans as the major products from the chiral formylcyclopropanes, CH acids, and Hantzsch ester. It is an efficient, catalytic, two-step protocol for the chiral synthesis of dihydropyrans and dihydrofurans. Structurally important and challenging functionally rich cyclopropanes containing cyclic-1,3-diones were synthesized in very good yields with excellent chemo-, enantio-, and diastereoselectivities from the readily available starting materials, chiral formylcyclopropanes, cyclic-1,3-diones, or CH acids and Hantzsch ester through an organocatalytic reductive coupling reaction at ambient conditions, especially without harming the cyclopropane ring.

Iodine-catalyzed tandem synthesis of terminal acetals and glycol mono esters from olefins.

A new metal-free protocol is described for the synthesis of terminal acetals by tandem oxidative rearrangement of olefins using oxone as an oxidant in the presence of iodine. Moreover, a one-pot procedure for the preparation of glycol mono esters from olefins is also presented for the first time using the same reagent system.