Diastereoselective Epoxidation of Oxazolidine-Substituted Alkenes by Dimethyldioxirane andm-Chloroperbenzoic Acid:  π-Facial Control through Hydrogen Bonding by the Urea Functionality

Abstract

[figure: see text] A high diastereoselectivity (up to > 98:2) is found for the DMD and m-CPBA epoxidations of chiral oxazolidine-substituted olefins with a urea group. The selectivity is explained in terms of hydrogen bonding between the remote NH group of the urea functionality and the epoxidizing reagent. Methylation of the NH group prohibits hydrogen bonding, and a reversed selectivity is observed due to steric repulsion between the reagent and the urea functionality.

InBr3 catalyzed tandem construction of C–C, C–O and C–N bonds: a concise, convenient and atom-economical strategy for the synthesis of spiro oxazolidine oxindole derivatives

“…However, on further decreasing the mol% of catalyst to 10 mol%, substantial decrease in the product yield was observed (entry 15). The amount of base also made a difference as on decreasing its amount from 1 mmol to 0.5 mmol, yield of the product decreases (entry 16) while on increasing to 1.5 mmol no change in the yield was observed (entry 17). We also ascertained that heating decreases the yield (entry 18).…”

“…Thus due to highly pronounced pharmacological activities displayed by these structurally diverse spirocyclic oxindole, it has attracted considerable attention from organic chemists, resulting in the development of biologically promising analogues that are often more efficacious than the original natural products 13,14 . Similarly, substituted oxazolidine moieties have been exploited successfully in medicinally valuable compounds such as the anticancer prodrugs doxazolidine, doxoform, and doxazcarbamate 15 and also as chiral auxiliaries for synthesis of many chiral compounds [16][17][18] Figure 1 Natural Products containing spirooxindole skeleton Significant attention has recently been paid to the use of indium salts as green Lewis acid in organic synthesis [19][20][21][22] . In many cases, indium halides have advantages of non-toxicity, stability in air and water and strong tolerance to oxygen-and nitrogen-containing substrates than the conventional lewis acids.…”

Chiral-Auxiliary-Controlled Diastereoselective Epoxidations

“…In the alkenes 8, equipped with a chiral oxazolidine auxiliary (Table 8), 38,39 the C-C double bond to be diastereoselectively epoxidized is located at the acetal-type chirality center of the oxazolidine ring. Usually, such a double bond is attached as a side chain to the carbonyl functionality at the oxazolidine nitrogen atom.…”

ChemInform Abstract: One‐Pot Microwave‐Assisted Synthesis of Novel Substituted N‐Dichloroacetyl‐4,5‐dimethyl‐1,3‐oxazolidines.

“…Oxazolidine derivatives are important target compounds with their biological activities, pharmacological activity and their extensive use as chiral auxiliaries for synthesis of many chiral compounds [7][8][9][10][11][12]. In addition, N-dichloroacetyl oxazolidines have been used as herbicide safeners in recent years [13].…”