Asymmetric UNDEC

ASYMMETRIC EPOXIDATION OF ( >UNDEC-2-EN-l-OL USING POLY(OCTAMETHYLENE TARTRATE)... 

Fig. 11. Fukugama s asymmetric synthesis of (-(-CP-263,114 intramolecular Diels—Alder reaction and formation of the maleic acid anhydride moiety. DBU = l,8-diazabicyclo[5.4.0]undec-7-ene, NIS = N-iodosuccinimide.

Asymmetric allylation is performed by chiral allylating reagents. The chiral allyltin generated in situ from benzodio-stannole [Sn(02C6H4)], allyl halide, chiral dialkyl tartrates and l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) reacts with aromatic aldehydes in the presence of copper salts to afford the chiral homoallyl alcohols (Equation (50)).164... 

AD-mix-P 9-BBN Bn Boc Bz BOM CDI m-CPBA CSA Cy DBU DDQ DEAD DIAD DIBAL-H DIPT DME DMF DMAP DMSO EDC HMPA HOBT KHMDS LDA MEM MOM MoOPH NaHMDS NBS NMM NMO Piv PMB Reagent for Sharpless asymmetric dihydroxylation 9-Borabicyclo[3.3.1 ]nonyl Benzyl t-Butoxy carbonyl Benzoyl B enzyloxy methyl Carbonyldiimidazole m-Chloroperoxybenzoic acid Camphorsulfonic acid Cyclohexyl 1,8 -Diazabicy clo[5.4.0] undec-7-ene 2,3 -Dichloro-5,6-dicyano-p-benzoquinone Diethyl azodicarboxylate Diisopropyl azodicarboxylate Diisobutylaluminum hydride Diisopropyl tartrate Dimethoxyethane A,N-Dimethylformamide 4-Dimethylaminopyridine Dimethyl sulfoxide N-(3-Dimethylaminopropyl)-A -ethylcarbodiimide Hexamethylphosphoramide 1 -Hydroxybenzotriazole Potassium hexamethyldisilazane Lithium diisopropylamide Methoxyethoxymethyl Methoxymethyl Oxidodiperoxymolybdenum(pyridine)(hexamethylphophoramide) Sodium hexamethyldisilazane N - Bromosuccinimide A-Methylmorpholine A-Methylmorpholine A-oxide Pivaloyl /j-Methoxybenzyl... 

One of the successful utilizations of the difference in the relative stability between fluorinated and nonfluorinated imines is an effective transformation of perfluorinated ketones to the perfluorinated amines via imines by base-catalyzed 1,3-proton-shift methodology [9]. The driving force for the proton shift from 31 to 32 arises from the relatively lower stability of perfluoroalkyl imines compared to benzylidene imines [9]. Soloshonok developed an asymmetric version of the transformation in which DBU (l,8-diazabicyclo[5.4.0]undec-7-ene) catalyzes the asymmetric 1,3-proton shift of 31 to provide enantio-enriched (3-aminoester (33), as shown in Scheme 1.20 [10]. 

Their structures were mainly determined by spectral studies using EI-MS, IR, H-NMR, NOE, and CD spectra (75). They consist of a main spiroether moiety, corresponding to 1-oxaspiro[5. 5]undec-4-ene-8-one ring system, (including seven asymmetric centers and possessing a (Z)-olefin, a mefa-substituted phenol, and a P-ketocarboxylic acid functions) and a P-hydroxy-y-lactone moiety. Oscillatoxin Ds are present as esters of both moieties. On the other hand, aplysiatoxins are present as macro bis-lactones including a spiroacetal. We are interested in the relationship between oscillatoxins and aplysiatoxins from a biosynthetic point of view. 

A unique inversion on the theme of trapping an electrophile with enolate nucleophile has been reported by Krishnan and Stoltz who have installed all-carbon quaternary centers at oxindoles, e.g., 42, in racemic fashion through the treatment of electrophilic 3-halooxindoles with nucleophilic malonates, e.g., 40-41, using DBU (l,8-diazabicyclo[5.4.0]undec-7-ene) for the deprotonation step (Scheme 11) [28]. An asymmetric variation of the chemistry in Scheme 11 has been reported by the same group who constructed enantioeiuiched oxindoles using catalytic Cu(ll)-Lewis acid and a chiral bis(oxazoline) ligand [29]. 

The asymmetric epoxidation of several acyclic a,/8-unsaturated ketones (RiC =C—COR ) in THF under aerobic conditions by H2O2—urea in the presence of l,6-diazabicyclo[5.4.0]undec-7-ene (DBU) to the corresponding epoxides in high yield (87-99%) was achieved using 11-/253,7/15 -10 heptapeptide (117) as the catalyst. Enantiomeric excess was excellent (99% ee) for R = Ph and R = 2-furanyl but moderate to high (72-88% ee) in other cases the yields were low for R = alkyl. ... 

Scheme 2.23 Generation of chiral 5.6-dihydropyran-2-ones via the asymmetric catalytic cycloaddition of a heterodiene to an olefin. Application to a synthesis of (+)-goniotriol (Pin, pinacolyl and DBU, l,8-diazabicyclo[5.4.0]undec-7-ene).

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