Waste DNA gets a second life: A Pd/DNA catalyst, which was prepared by a facile method, has high activity for the selective hydrogenation of carboncarbon triple bonds, carbon–carbon double bonds, and nitro groups, as well as for the Suzuki–Miyaura coupling reaction.

We developed a highly reactive catalytic ring-closing ene reaction with chiral aluminum complexes. Kinetic resolutions of citronellal successfully afforded 68% ee of diastereoselective isopulegol and 62% ee of citronellal at 47% conversion with the BINOL-Al catalyst. l-Menthol was synthesized from citral with kinetic resolutions.

We have demonstrated that a combination of enantiopure 2-diarylmethylpyrrolidines and heterogeneous Pd/BaSO(4) is an efficient catalytic system for the asymmetric hydrogenation of citral, specifically, a mixture of E-citral and Z-citral in any ratio, and that citronellal is obtained with high enantioselectivity. This dual catalyst system provides a new and more economical route to L-menthol.

An aluminium complex bearing 2-cyclohexyl-6-phenylphenol afforded (5R)-n-isopulegol from (R)-citronellal via the intermolecular Prins reaction with an exceptionally high diastereoselectivity. Using this reaction, L-menthol was obtained with an excellent diastereoselectivity.Intermolecular and intramolecular ene reactions, especially the Prins reaction between carbonyl and olen compounds with Lewis or Brønsted acids, have received great attention. 1 A common application of the Prins reaction is the synthesis of (5R)-isopulegols (2) from (R)-citronellal ((R)-1) (Scheme 1).These are valuable intermediates for the synthesis of Lmenthol (3), one of the most popular fragrances in the world; 2 notably, only (5R)-n-isopulegol (2a) leads to the formation of (3). Hence, a variety of methods has been reported for the diastereoselective cyclisation of citronellal to isopulegol. 3-10 For instance, zinc bromide is used as a catalyst for this cyclisation in an industry process, which provides 2a with 92% of diastereomeric purity. 4a In addition, various other aluminium complexes have been recently proposed as only catalysts that afford (5R)isopulegols with a high diastereoselectivity. 11-14 For instance, tris(2,6-diphenylphenoxy)aluminium complex (ATPH, 4a), 14 which was prepared from triethylaluminium and 2,6-diphenylphenol (5a), has been used to carry out the Prins reaction of citronellal with a diastereoselectivity larger than 99% and 94% selectivity of 2 at 0 C. 11 However, 4a shows the excellent performance in a narrow temperature range. So, it's demanded a catalyst that provides higher reactivity and same diastereoselectivity, in order to apply it to a variety of industrial processes. In this work, we present aluminium catalysts with unprecedented excellent diastereoselectivity for the citronellal cyclisation.Firstly, we prepared tris(2-cyclohexyl-6-phenylphenoxy) aluminium complex (ACPP, 4b) with triethylaluminium and 2cyclohexyl-6-phenylphenol (5b). (R)-Citronellal ((R)-1) gave (5R)n-isopulegol (2a) in the presence of ACPP with 78% conversion, 95% selectivity of (5R)-isopulegols (2) and diastereoselectivity larger than 99% at À20 C while ATPH (4a) afforded 2a with 54% conversion (Scheme 2). A catalyst with such an excellent selectivity and reactivity has never been reported.We next investigated the reactivity of ACPP with a variety of reaction conditions. In particular, 3 mol% of ACPP afforded Scheme 1 Synthesis of L-menthol (3) from (R)-citronellal (1).

We report a highly selective asymmetric ring-closing ene reaction catalysed by aluminum complexes with chiral BINOL. This reaction yields optically active 6-membered cyclized alcohols from unsaturated aldehydes, with good diastereo- and enantioselectivities. Asymmetric amplification of this reaction was investigated by varying the ee of the BINOL employed in the catalyst.

Correction for ‘Highly selective aluminium-catalysed intramolecular Prins reaction for l-menthol synthesis’ by H. Itoh et al., RSC Adv., 2014, 4, 61619–61623.

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Enantioselective Binding and Extraction of Zwitterionic Amino Acids by Chiral Lanthanide Complexes. --(TSUKUBE, H.; UENISHI, J.; KANATANI, T.; ITOH, H.; YONEMITSU, O.; Chem.