Enantioselective Prévost and Woodward reactions using chiral hypervalent iodine(iii): switchover of stereochemical course of an optically active 1,3-dioxolan-2-yl cation

Abstract

Optically active 1,3-dioxolan-2-yl cation intermediates were generated during enantioselective dioxyacetylation of alkene with chiral hypervalent iodine(III). Regioselective attack of a nucleophile toward the intermediate resulted in reversal of enantioselectivity of the dioxyacetylation.

Highly Enantioselective Iron‐Catalyzed cis‐Dihydroxylation of Alkenes with Hydrogen Peroxide Oxidant via an FeIII‐OOH Reactive Intermediate

“…For electron-rich (E)-alkenes,s ubstituted 1-phenyl propenes led to 87.4-89. 3 [11] better enantioselectivity, improved product yields,a nd broader substrate scope have been observed in this work, and the selectivity of cis-diols increased significantly (epoxide and C=Cbond cleavage side products formed in < 1% yield).…”

Alternative Strategies with Iodine: Fast Access to Previously Inaccessible Iodine(III) Compounds

“…For both reactions,s imilar yields and selectivities were obtained with both preformed or in situ generated iodine(III) reagent 13 d.A saresult of the regioselective iodination, the iodine-(III) moiety is not placed in between the two chiral substituents in 13 d.T his can be overcome by treating 12 e with 4.Diacetoxylation of styrene (15)with 13 e improved the enantiomeric excess of 16 to 58 %, which is slightly less than in ap reviously described reaction (70 % ee)w ith as imilar hypervalent iodine reagent under the same conditions. [23] The lower enantiomeric excess presumably results from ah igher electron density in 13 e through the third oxygen substituent. Ther earrangement of 19 to 20 was also performed using the reagent 13 e generated in situ.…”

Chiral Hypervalent Iodine Reagents: Synthesis and Reactivity

“…In 2011, the same authors51 developed an interesting variant for the preparation of optically active 1,3‐dioxolan‐2‐yl cation, employing it in Prévost and Woodward reactions (Scheme ). The enantioselective oxylactonization of alkenes 131 mediated by lactate‐derived aryl‐λ 3 ‐iodanes ( R )‐ 132 a , b or ( R , R )‐ 127 was subsequently followed by a nucleophilic attack that allowed the selective formation of a specific adduct according to the nature of the nucleophile.…”