Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• fair yield of this two-step transformation may be the consequence of the aldehyde’s low stability. Note that the Kotsuki method to perform the Robinson-type annulation of 9 with EVK, catalyzed by a combination of 1,2-cyclohexanediamine and 1,2-cyclohexanedicarboxylic acid, led to product 12 with higher

Bioinspired tetraamino-bisthiourea chiral macrocycles in catalyzing decarboxylative Mannich reactions

• Hao Guo,
• Yu-Fei Ao,
• De-Xian Wang and
• Qi-Qiang Wang

Beilstein J. Org. Chem. 2022, 18, 486–496, doi:10.3762/bjoc.18.51

• , hetero-condensations between different bisamine and bisisothiocyanate fragments, including combination of different chiral configurations, were also investigated (Scheme 1c). Reactions between cyclohexanediamine-derived bisamine fragments 4a or the enantiomers ent-4a–c with diphenylethylenediamine

• on the reaction stereoselectivity. The cyclohexanediamine-linking macrocycles M1–M4 afforded the product with overall higher enantiomeric excess (ee) (Table 1, entries 1–4). Among which the isopropyl-substituted macrocycle M3 gave the best selectivity, i.e., 42% ee. This suggested a suitable crowding

• reversed selectivity, which may imply that the chiral cyclohexanediamine other than diphenylethylenediamine moiety governed the stereoselection process. Using M3 as the optimal catalyst, the reaction solvent was then screened (Table 2). Ethyl ether was found to give a better conversion, but with decreased

Copolymerization of epoxides with cyclic anhydrides catalyzed by dinuclear cobalt complexes

• Yo Hiranoi and
• Koji Nakano

Beilstein J. Org. Chem. 2018, 14, 2779–2788, doi:10.3762/bjoc.14.255

• (Scheme 1) [40]. First, the reaction of bis(salicylaldehyde) 5 with (R,R)-half-salen 6, which was prepared from (R,R)-1,2-cyclohexanediamine monohydrochloride and 3-tert-butyl-5-fluoro-2-hydroxybenzaldehyde, gave monosalen (R,R)-7 in 39% yield. Then, the obtained mono(salen) (R,R)-7 was converted into the

• ,R)-1,2-cyclohexanediamine monohydrochloride (0.14 g, 0.93 mmol), 3-tert-butyl-5-fluoro-2-hydroxybenzaldehyde (0.18 g, 0.93 mmol), molecular sieves 4Å, and dry MeOH (1.5 mL) under argon. After stirring at room temperature for 50 min, the resulting solution was slowly transferred to another Schlenk

• , 24.34, 24.29; 19F NMR (471 MHz, CDCl3) δ −126.3; HRMS–APCI+ (m/z): [M + H]+ calcd for C47H54FN2O8, 793.3859; found, 793.3859. Synthesis of bis(salen) (R,R,S,S)-8: The crude product was obtained from (S,S)-1,2-cyclohexanediamine monohydrochloride (28 mg, 0.19 mmol), 3-tert-butyl-5-fluoro-2

Asymmetric Michael addition reactions catalyzed by calix[4]thiourea cyclohexanediamine derivatives

• Zheng-Yi Li,
• Hong-Xiao Tong,
• Yuan Chen,
• Hong-Kui Su,
• Tangxin Xiao,
• Xiao-Qiang Sun and
• Leyong Wang

Beilstein J. Org. Chem. 2018, 14, 1901–1907, doi:10.3762/bjoc.14.164

• Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China 10.3762/bjoc.14.164 Abstract A number of upper rim-functionalized calix[4]thiourea cyclohexanediamine derivatives have been designed, synthesized and used as catalysts for enantioselective Michael addition reactions between

• clearly showed that the upper rim-functionalized hydrophobic calixarene scaffold played an important role in cooperation with the catalytic center to the good reactivities and enantioselectivities. Keywords: asymmetric Michael addition reaction; calix[4]arene; cyclohexanediamine; thiourea; Introduction

• reactions in aqueous solution with excellent enantioselectivity [35]. As part of our ongoing studies to develop novel types of organocatalysts for asymmetric catalysis, in this study, we aimed to synthesize novel upper rim-functionalized calix[4]thiourea cyclohexanediamine derivatives to catalyze asymmetric

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

• Lingjun Xu,
• Shuwen Han,
• Linjie Yan,
• Haifeng Wang,
• Haihui Peng and
• Fener Chen

Beilstein J. Org. Chem. 2018, 14, 309–317, doi:10.3762/bjoc.14.19

• ][20] and valine [21] etc. [22][23][24][25][26][27][28][29], while fully synthetic catalysts are rare, only involving Brønsted acid/base catalysts [30], cyclohexanediamine catalysts [31][32], and diphenylethylenediamine catalysts [33][34]. Significant progress in our laboratory has been made in the

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• ) [65]. Interestingly, the optimal organocatalyst for the transformation was chiral only at sulfur, when chiral amine motifs were explored, e.g., 1,2-cyclohexanediamine, poor enantioselectivity was observed (≤75:25 er). A variety of R1 substituents on Meldrum’s acid 156 were compatible with the reaction

Studies on the synthesis of peptides containing dehydrovaline and dehydroisoleucine based on copper-mediated enamide formation

• Franziska Gille and
• Andreas Kirschning

Beilstein J. Org. Chem. 2016, 12, 564–570, doi:10.3762/bjoc.12.55

• 3). The presence of the ligand was essential and the choice of other amines such as tetramethylethylendiamine (TMEDA) (Table 1, entry 4) or piperidine-2-carboxylate did not lead to product formation (Table 1, entry 5). However, (rac)-trans-N,N-dimethyl-1,2-cyclohexanediamine (17) [9] in combination

Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

• Antonia Di Mola,
• Maximilian Tiffner,
• Francesco Scorzelli,
• Laura Palombi,
• Rosanna Filosa,
• Paolo De Caprariis,
• Mario Waser and
• Antonio Massa

Beilstein J. Org. Chem. 2015, 11, 2591–2599, doi:10.3762/bjoc.11.279

• previous version developed on the racemates (Scheme 5) [36]. This method also allowed us to obtain the analogues 21 and 22 of the bioactive isoindolinones described in Figure 1 in high overall yield (50%) without loss in enantiomeric purity. Conclusion Recently developed (R,R)-1,2-cyclohexanediamine-based

Organocatalytic and enantioselective Michael reaction between α-nitroesters and nitroalkenes. Syn/anti-selectivity control using catalysts with the same absolute backbone chirality

• Jose I. Martínez,
• Uxue Uria,
• Maria Muñiz,
• Efraím Reyes,
• Luisa Carrillo and
• Jose L. Vicario

Beilstein J. Org. Chem. 2015, 11, 2577–2583, doi:10.3762/bjoc.11.277

• syn-3a in excellent yield, an acceptable 88:12 dr and 98% ee. As expected, the use of the pseudoenantiomeric catalyst 5 provided the corresponding enantiomer ent-syn-3a with similar results. Moving to cyclohexanediamine-based catalyst 6 resulted in the same behaviour as observed in our previous report

• cyclohexanediamine/squaramide catalyst 6 which, as mentioned before, is based on a chiral backbone with the same absolute chirality as 4. The reaction conditions used for this reaction were those already observed to be optimal in our previous work for the cascade Michael/Henry reaction using this catalyst, that

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• -(tert-butyl)salicylaldehyde (5) [24][25][26][27]. 5-N,N-Dimethylamino-3-(tert-butyl)salicylaldehyde (6) was prepared directly from 5, using a literature procedure [28][29]. The salen ligand 7 was then obtained in high yield by condensation with (R,R)-cyclohexanediamine, according to a known technique

The enantioselective synthesis of (S)-(+)-mianserin and (S)-(+)-epinastine

• Piotr Roszkowski,
• Jan. K. Maurin and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2015, 11, 1509–1513, doi:10.3762/bjoc.11.164

• ruthenium complex 11 which contain (1R,2R)- or (1S,2S)-N-tosyl-1,2-cyclohexanediamine as chiral ligand (Figure 2). The reaction was carried out in acetonitrile using an azeotropic mixture of formic acid/triethylamine as hydrogen source with 50:1 substrate to catalyst ratio. Under these conditions the