BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• desymmetrization of meso-1,2-diols [58]. The [2]rotaxane (R)-42 was synthesized by interaction of the ammonium salt 41 with the BINOL-based macrocycle (R)-12 and end-capping with 3,5-di-tert-butylbenzoic acid (see Figure 10). In the asymmetric desymmetrization reaction of meso-hydrobenzoin, rotaxane (R)-42 gave

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

Asymmetric desymmetrization of meso-diols by C₂-symmetric chiral 4-pyrrolidinopyridines

• Hartmut Schedel,
• Keizo Kan,
• Yoshihiro Ueda,
• Kenji Mishiro,
• Keisuke Yoshida,
• Takumi Furuta and
• Takeo Kawabata

Beilstein J. Org. Chem. 2012, 8, 1778–1787, doi:10.3762/bjoc.8.203

• the catalyst and the substrate may not significantly be involved in the process of enantioselective acylation of 19 in the presence of catalysts 4 and 11. Asymmetric desymmetrization of meso-2,3-butanediol and meso-hydrobenzoin The asymmetric desymmetrization of meso-2,3-butanediol (22a) and meso

• -hydrobenzoin (22b) were examined (Table 6). Treatment of 22a with isobutyric anhydride in the presence of 5 mol % of catalyst 8a at 20 °C for 4 h gave monoacylate 23a in 53% ee and 78% yield (Table 6, entry 1). Catalysts 10, 11, 12b, and 14 were also examined for asymmetric desymmetrization of 22a (Table 6

• 168 h.) The asymmetric desymmetrization of meso-hydrobenzoin (22b) was examined. Treatment of 22b with isobutyric anhydride in the presence of catalysts 8a, 8b, and 12b at 20 °C gave 23b in 19–40% ee in 54–64% yield (Table 6, entries 9–11). Significant amounts of the diacylate were also formed (22–25

Photoreactions of cyclic sulfite esters: Evidence for diradical intermediates

• Rick C. White,
• Benny E. Arney Jr. and
• Heiko Ihmels

Beilstein J. Org. Chem. 2012, 8, 1208–1212, doi:10.3762/bjoc.8.134

• meso-hydrobenzoin sulfite undertaken about four decades ago stated that these compounds are also carbene precursors [16], in analogy to the results obtained with carbonate 1b. To provide further insight into the mechanism of the photoinduced cleavage of the cyclic sulfites, we examined the styrene

• glycol sulfite (8) and the hydrobenzoin sulfite (9); and we herein demonstrate that diradical intermediates are generated during the photoextrusion processes. Results and Discussion Styrene glycol sulfite 8 was prepared from thionyl chloride and styrene glycol in the presence of triethylamine [19]. The

• investigated the photochemistry of hydrobenzoin sulfite (9), which has been reported also to be a carbene precursor [16]. Because it has been shown in the case of cyclic carbonates that the application of milder reaction conditions enables the detection of reaction products that apparently decompose under

Directed ortho,ortho'-dimetalation of hydrobenzoin: Rapid access to hydrobenzoin derivatives useful for asymmetric synthesis

• Inhee Cho,
• Labros Meimetis,
• Lee Belding,
• Michael J. Katz,
• Travis Dudding and
• Robert Britton

Beilstein J. Org. Chem. 2011, 7, 1315–1322, doi:10.3762/bjoc.7.154

• .7.154 Abstract A variety of ortho,ortho'-disubstituted hydrobenzoin derivatives are readily accessible through a directed ortho,ortho'-dimetalation strategy in which the alcohol functions in hydrobenzoin are deprotonated by n-BuLi and the resulting lithium benzyl alkoxides serve as directed metalation

• groups. The optimization and scope of this reaction are discussed, and the utility of this process is demonstrated in the one-pot preparation of a number of chiral diols as well as a short synthesis of the chiral ligand Vivol. Keywords: chiral diol; directed ortho-metalation; hydrobenzoin; Introduction

• reactions promoted by these ligands and/or their derivatives. Although hydrobenzoin (e.g., 3) has not been utilized to the same extent, it has also demonstrated utility as both a chiral ligand [3][4][5][6][7][8] and auxiliary [9][10][11][12][13][14][15][16][17]. For example, Hall reported that the