Molecular structures of the most prominent chiral non‐racemic hypervalent iodine(III) reagents to date have been elucidated for the first time. The formation of a chirally induced supramolecular scaffold based on a selective hydrogen‐bonding arrangement provides an explanation for the consistently high asymmetric induction with these reagents. As an exploratory example, their scope as chiral catalysts was extended to the enantioselective dioxygenation of alkenes. A series of terminal styrenes are converted into the corresponding vicinal diacetoxylation products under mild conditions and provide the proof of principle for a truly intermolecular asymmetric alkene oxidation under iodine(I/III) catalysis.

Hypervalent iodine(III) reagents have been known for over a century, and their reaction profile is still actively investigated. Recent years have seen impressive improvements in the area of alkene difunctionalization reactions, where new methodologies have become available. Especially chiral non-racemic hypervalent iodine(III) reagents and catalysts have emerged as versatile tools for the realization of important enantioselective transformations.

The catalytic asymmetric Fujiwara-Moritani ring closures of several indole-and pyrrole-based cyclization precursors are reported. These unprecedented oxidative palladium(II)-catalyzed annulations allow for the formation of a stereogenic quaternary carbon atom, and decent levels of enantiocontrol are seen in 5-exo-trig cyclizations (54 % ee for an indole and 76 % ee for a pyrrole) while 6-exo-trig ring closures afford

2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) was employed as chiral ligand in the enantioselective intermolecular Mizoroki-Heck reaction, whereas the use of cognate BINAP(O) (monooxidized BINAP) is unprecedented. The regio- and enantioselectivity of the arylation of representative cyclic alkenes changes dramatically in the presence of hemilabile BINAP(O) instead of BINAP. The arylation of 2,3-dihydrofuran is perfectly regiodivergent (98:2 versus 0:100) and the arylation of cyclopentene is only enantioselective with BINAP(O) [60 versus 10% enantiomeric excess (ee)]. Use of [Pd(2)(dba)(3)]⋅dba (dba=dibenzylideneacetone) instead of Pd(OAc)(2) produces as high as 86% ee in the arylation of cyclopentene.

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BINAP(O), rarely used as a chiral ligand, was found to induce significantly higher levels of enantioselection in representative desymmetrizing Mizoroki–Heck cyclizations where conventional BINAP produces essentially racemic material. BINAP(O) is a ligand with a stronger and weaker donor atom, and that hemilabile nature lends itself the ability to act as either a bi‐ or monodentate ligand. On that basis, we introduce mechanistic models where the weak donor, in one case, mediates the equilibration of diastereomeric alkene–palladium(II) complexes and, in another case, dissociates from the palladium(II) atom, thereby rendering BINAP(O) as a monodentate ligand. These new findings, along with the recently reported effects in intermolecular Mizoroki–Heck reactions, suggest that BINAP(O) ought to be included into ligand screenings.

A procedure for the intermolecular enantioselective dioxygenation of alkenes under iodine(III) catalysis has been developed. This protocol employs Selectfluor as the terminal oxidant together with a defined C 2 -symmetric aryl iodide as the organocatalyst. This enantioselective reaction proceeds under mild conditions and converts a series of terminal and internal styrenes into the corresponding vicinal diacetoxylation products with up to 96% ee.Key words alkenes, chirality, diacetoxylation, hypervalent iodine, oxi- dation, SelectfluorAs a synthetic concept, the vicinal difunctionalization of alkenes allows for a rapid structural and functional diversification of simple alkene moieties within a single operation. 2 Among the many examples of this type of reactions, the development of processes that proceed entirely under intermolecular reaction control is of particular challenge. While this field has been largely dominated by enantioselective transition metal catalysis such as the seminal osmium-based dihydroxylation and aminohydroxylation processes developed by Sharpless, 3 chiral nonracemic iodine(III) reagents 4 have recently emerged as potentially versatile alternatives. 5 Based on earlier work on defined iodine(III) reagents for selective dioxygenation of alkenes, 5c,6 the development of the corresponding enantioselective dioxygenation reactions was pioneered and extensively investigated by Wirth. 7 These reactions made use of defined chiral iodine(III) reagents such as 1, and the oxidation of styrene 2a led to the formation of the corresponding ditosylation product 3a′ with up to 65% ee (Scheme 1). The appearance of the chiral bislactate derived iodine(III) oxidant 4a has greatly advanced the inherent synthetic possibilities, 5,8 and, based on this reagent, an enantioselective diacetoxylation of 2a subsequently led to the formation of the corresponding diacetoxylated product 3a in up to 89% ee (Scheme 1). 9 A related diamination 10 was also developed using stoichiometric amounts of 4a. Moreover, an amide derivative of 4a promoted an oxygenative rearrangement reaction, 11a an Umpolung functionalization of silylated enol ethers, 11b and asymmetric Kita-spirolactonization reac-