74839-83-1

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Asymmetric synthesis of (R,R)- and (S,S)-1,8,9,16- tetrahydroxytetraphenylenes was achieved from starting material (2R,3R)-butane-2,3-diol and (2S,3S)-butane-2,3-diol respectively by utilizing a center-to-axis strategy. A series of crown ether compounds 20, 24, and 25 and their corresponding enantiomers derived from chiral tetrahydroxytetraphenylene were synthesized in enantiomerically pure forms. Enantiomeric recognition properties of these hosts toward l- and d-amino acid methyl ester hydrochloride were studied by the UV spectroscopy titration. The tetramer hosts (S,S,S,S,S,S,S,S)-20 and (R,R,R,R,R,R,R,R)-20 exhibited the best enantioselectivities toward l- and d-alanine methyl ester hydrochloride salt with KL/KD = 4.1 and KD/KL = 3.9, respectively. The new chiral macrocyclic hosts would further enrich the host-guest chemistry.

This invention relates to a chromium complex compound for selective ethylene oligomerization including a chiral ligand, and to a method of selectively preparing 1-hexene or 1-octene from ethylene using the same.

Enantiomerically pure 1,2-diols bearing optionally syn or anti configurated secondary hydroxylic groups are synthesized from acetal-protected cyanohydrins.After resolution of the diastereomers the cyanohydrins are converted into α-alkoxy-ketones by Grignard-reaction followed by reduction using common chelating or non-chelating agents.Among others syntheses of enantiomerically pure pheromones, endo-Brevicomin, exo-Brevicomin and Dispalure are given as examples.

Treatment of β-keto-acetals, derived from non-enolisable β-diketones, with sulfonic acids in boiling benzene results in a smooth retro-Claisen-type fragmentation.The acetal-C-atom is thereby transformed into a carboxylic ester via a dialkoxycarbenium ion, which is dealkylated by the sulfonate counter-ion.Application of this reaction to the diastereomeric monoacetals 3 and 4, derived from cis-9-methyl-decalin-1,8-dione (1), followed by transesterification with CH3OH, yields optically pure 4-(2'-methyl-3'-oxocyclohexyl)butyrate 9 ((+)-9 from 3, (-)-9 from 4) and the monosulfonate of meso-2,3-butanediol (-)-13 (Scheme 2).Unexpected, this cleavage proceeds as well with monoacetal 26, obtained by acetalization of trans-9-methyl-decalin-1,8-dione (27) with 2,2-dimethyl-1,3-propanediol (Scheme 7).Some attempts, aiming at an isomerization of the cis- and trans-decalin derivatives 3 and 24, or 25 and 26, via the postulated carboxonium intermediate, were not successful.

Rhodium(I) complexes of the new chiral ligand (2R,3R)-2,3-bis(diphenylphosphino)butane (4) - which is easily prepared from natural tartaric acid - hydrogenate α-(acylamino)acrylic acids to natural (S)-acylamino acids in high chemical (95-100percent) and optical (80-100percent) yields.