Brucine diol

If 2-camphanyloxyacrylonitrile (15 R = C8H 02C00) is taken for cycloaddition, diastereoisomeric cycloadducts can be separated, and the basic system, 7-oxabicyclo-[2.2.1]hept-5-en-2-one 17, can be obtained in optically pure form [36]. Another way of obtaining enantiomeric ketones is based on crystallization of a brucine complex obtained from the corresponding cyanohydrines (see Sec. III). Ketone 17 can be converted [e.g., by cis-hydroxylation (—>18), protection of the diol system, and Baeyer-Villiger oxidation] to lactone 19, the opening of which leads to furanuronic acid 20. A new development in this field is based in cycloaddition between furan and 2-chloro- or 2-bromoacrolein in the presence of 5 mol% chiral oxazaborolidine 21 as catalyst [37],... 

Furan adds to vinylene carbonate to produce an exolendo mixture of Diels-Alder adducts [165]. Double hydroxylation of the 7-oxanorbornene double bond is highly exo face selective (Scheme 13.88). The diol thus obtained is protected as an acetonide. Saponification of the carbonate liberates a mixture of diols that is oxidized into m 5 6>-l,5-anhydroallaric acid derivative 316. Treatment of 316 with AC2O generates the anhydride 317. Subsequent reaction of 317 with methanol gives racemic 318 that can be resolved by fractional crystallization with brucine or by chromatographic separation of the (7 )-l-((3-naphthyl)ethylamides. The individual isomers of 318 each react with ClCOOEt and Me3SiN3 in situ to provide enantiomerically pure d- and L-riboside derivatives [166]. 

Clathrates of [tri-O-thymotide (TOT), brucine, sparteine, 2,2 -dihydroxy-1,1 -binaphthyl-diol] Alkanes, unbranched chiral hydrocarbons, acids and esters bearing small substituents, halogenated hydrocarbons, sulfoxides, phosphine oxides, phosphinates, piperidines [59-64]... 

ABSTRACT. Novel optical resolutions of guest compounds by inclusion complex formation with optically active host compound are reviewed Tertiary acetylenic alcohols, cyanohydrins, and secondary alcohols were resolved by complexation with alkaloids such as brucine or sparteine. Cycloalkanones, 2,3 -epoxycyclohexanones, and some other neutral compounds were resolved by complex formation with optically active diacetylenic diol. Mutual optical resolution of bis-g-naphthol and sulfoxides by complex formation was also reviewed. 

On the other hand, another cooperative catalysis approach was developed by Oh and Kim with a highly diastereo- and enantioselective domino aldol-cyclisation reaction occurring between aldehydes and methyl a-isocyanoacetate. The process employed a combination of a chiral cobalt complex derived from brucine amino diol and an achiral thiourea. The reaction was applicable to a range of aliphatic, aromatic and heteroaromatic aldehydes, providing the corresponding chiral oxazolines in good yields and diastereoselectivities of up to >90% de combined with good to excellent enantioselectivities of up to 98% ee, as shown in Scheme 7.12. 

Without the formation of an ethylene ketal protective grouping, the diol (70) was resolved into its optical isomers by crystallizing the brucine salts of the 14-hemisuccinates [661] or the strychnine salts of the 14-hemi-... 

Latifolic acid is one of the hydrolysis products of latifoline (Table 3 O i) it was shown to have the (2 5, 3 5, 4 R)-absolute configuration (53) by Matsumoto etal 201). The racemic ( )-isomer (49) was resolved with brucine, and the absolute configuration of one enantiomer was established by conversion of the methyl ester (50) into S)- - )-2-methylbutane-1,4-diol (51) (Scheme 16). The butyrolactones (52) and (54) formed by cis-hydroxylation of (50) were separated and identified by comparison with racemic material prepared earlier 200). Hydrolysis of (52) gave an acid which was identical with latifolic acid (53). 

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