Asymmetric Methoxyselenenylations with Chiral Selenium Electrophiles

Abstract

Very simple, chiral, non-racemic diselenides were prepared and their corresponding selenium electrophiles were used for the stereoselective functionalization of alkenes. The influ-

Rational Design of Chiral Selenium-π-Acid Catalysts

“…Treatment of substrate 1 with 1.1 equivalent of NFSI in the presence of 5 mol% of catalyst 4 at ambient temperature did not result in any product formation (Equation (1)). Based on this observation, we speculated that the presence of Lewis-basic residues in the proximity of the selenium atom under the title conditions may result in the formation of catalytically inactive selenonium species [14,23]. We therefore turned our attention toward the design of complementary molecular architectures that would still display pronounced conformational rigidity.…”

“…Since a broad variety of chiral phosphoric acid derivatives are commercially available, we felt that such a catalytic motif may bear the advantage of facile structural diversification. Thus, to exemplarily probe the synthetic feasibility of such a catalyst, 2-hydroxyphenyldiselenide (19) was synthesized in 30% in a single step from 2-bromophenol (Scheme 5) [14]. The resulting diselenide was then reacted with (R)-BINOL chlorophosphoric diester (18) [37] to give corresponding chiral catalyst 20 in 21% isolated yield.…”

“…Among these transformations, those catalyzed by selenium-π-acids represent by far the smallest subcategory [10][11][12]. This circumstance is to some degree surprising since stoichiometric diastereoselective selenofunctionalizations of simple alkenes with chiral, non-racemic selenium electrophiles have been on record for quite some time [13][14][15][16][17]. In general, these reactions proceed through the stereospecific attack of a given selenium electrophile onto an alkene (I), resulting in the transient formation of seleniranium intermediate II (Scheme 1) [18,19].…”

Azomethine diselenides: Supramolecular structures and facile formation of a bis-oxazoline diselenide

“…Particularly, the chemistry of intramolecularly coordinated organoselenium compounds has received a great deal of attention [13]. Diorgano diselenides are being used as a) electrophilic reagents in organic reactions [3,14,15], b) ligands for coordination chemistry [2,16] and catalysis [17,18] and c) synthetic model for glutathione peroxidase enzymes [19]. Organic diselenides create supramolecular arrangement with Se/X (X ¼ heteroatom) interactions.…”

Synthesis of selenoureas and heterocycles based thereon

“…Much attention has been given to the elaboration of new highly efficient methods for the synthesis of chiral organoselenium compounds [9]. Organoselenium compounds are used as ligands in asymmetric catalysis [10] and promising "green chemistry" catalysts [11].…”