Asymmetric synthesis of (+)-L-733,060

A concise, stereocontrolled synthesis of (+)-L-733,060 was achieved. Key features involve diastereoselective oxazoline formation catalyzed by palladium(0) and intramolecular cyclization by catalytic hydrogenation of an oxazoline.     

A short enantioselective synthesis of (−)-chloramphenicol and (+)-thiamphenicol using tethered aminohydroxylation

An efficient enantioselective synthesis of (−)-chloramphenicol (1) and (+)-thiamphenicol (2) is described. These antibiotics have been synthesized from commercially available 4-nitrobenzaldehyde and 4-(methylthio)benzaldehyde, respectively, using tethered aminohydroxylation and Sharpless asymmetric epoxidation as the chirality inducing steps.     

A short enantioselective synthesis of (+)-eleutherin, (+)-allo-eleutherin and a formal synthesis of (+)-nocardione B

A short enantioselective synthesis of (+)-eleutherin, (+)-allo-eleutherin and the formal synthesis of (+)-nocardione B is described. The synthesis is completed in six steps in overall yields of 8% for eleutherin and 14% for allo-eleutherin. The synthetic strategy features an efficient combination of the Dötz annulation reaction with a chiral alkyne and an oxa-Pictet Spengler reaction as the keys steps in the stereodivergent synthesis of (+)-eleutherin and (+)-allo-eleutherin. The synthesis of (S)-(+)-2-(2′-hydroxypropyl)-5-methoxy-1,4-naphthoquinone entails the formal synthesis of (+)-nocardione B.     

A stereoselective synthesis of (+)-L-733,060 from ethyl (R)-(+)-2,3-epoxypropanoate

An asymmetric synthesis of neurokinin substance P receptor antagonist (+)-L-733,060 starting from enantiomerically pure ethyl (R)-(+)-2,3-epoxypropanoate (ethyl glycidate) is described. The synthesis relies on a diastereoselective reductive amination, regioselective intramolecular epoxide opening, and in situ cyclization as the key steps.     

Chiral terpene auxiliaries. Part 1: Highly enantioselective reduction of ketones with borane catalyzed by an oxazaborolidine derived from (−)-β-pinene

(1R,2S,3R,5R)-3-Amino-6,6-dimethyl-2-hydroxybicyclo[3.1.1]heptane was synthesized in three steps from (−)-β-pinene. It was used for the in situ generation of a B-methoxy-oxazaborolidine catalyst for the asymmetric reduction of alkyl-aryl ketones with borane-dimethyl sulfide complex. In the presence of 3 mol % of the catalyst, the product alcohols were obtained in high yields and with enantiomeric excesses in the range of 93-98%.     

A practical synthesis of N-aryl-substituted oxazolidinone-containing ketone catalysts for asymmetric epoxidation

N-Aryl-substituted oxazolidinone-containing ketone catalysts for the asymmetric epoxidation of olefins can be efficiently prepared from d-glucose and anilines.     

First enantioselective synthesis of methyl (+)-7-methoxyanodendroate, an antitubercular dihydrobenzofuran

An enantioselective synthesis of methyl (+)-7-methoxyanodendroate was achieved utilising a Claisen rearrangement, a Grubbs cross-metathesis, and a Shi epoxidation-cyclisation sequence, confirming the absolute configuration assigned to the natural product.     

A three-step total synthesis of goniothalesdiol A using a one-pot Sharpless epoxidation/regioselective epoxide ring-opening

Using a one-pot Sharpless asymmetric epoxidation/regioselective epoxide ring-opening as a key step, the protecting-group-free total synthesis of goniothalesdiol A was accomplished in only three steps starting from commercially available trans-cinnamaldehyde in 55.1% overall yield. In 6 previously reported total syntheses, 6–11 steps were required.     

Concise asymmetric synthesis of (+)-CP-99,994 and (+)-L-733,060 via efficient construction of homochiral syn-1,2-diamines and syn-1,2-amino alcohols

An efficient asymmetric synthesis of human NK-1 SP receptor antagonists (+)-CP-99,994 and (+)-L-733,060 was achieved starting from a common chiral intermediate (5). Our route featured the SmI2-induced reductive coupling of N-tert-butanesulfinyl imine (7) with aldehyde (6) as the key step as well as pivotal transformations of the anti-1,2-amino alcohol thus obtained to homochiral syn-1,2-amino alcohol and syn-1,2-diamine for the asymmetric synthesis of 2,3-disubstituted piperidines.     

Enantioselective total synthesis of (+)-sarcandralactone A

An enantioselective total synthesis of the lindenane sesquiterpene (+)-sarcandralactone A has been accomplished for the first time. The synthesis features a SeO₂-mediated [2,3]-sigmatropic rearrangement for the facile construction of the tertiary allylic alcohol as a single diastereoisomer.     

A new, enantioselective synthesis of (+)-isolaurepan

A highly enantioselective synthesis of 2,6-syn-disubstituted tetrahydropyrans from commercially available tri-O-acetyl-d-glucal, based on a thermal Claisen rearrangement, allows enantioselective synthesis of (+)-isolaurepan when combined with a ring expansion reaction using trimethylsilyldiazomethane.     

Indium-mediated Barbier-type allylation of aldehydes as a convenient method for the highly enantioselective synthesis of homoallylic alcohols

We report a general method for the indium-mediated Barbier-type enantioselective allylation of both aromatic and aliphatic aldehydes using commercially available (1S,2R)-(+)-2-amino-1,2-diphenylethanol as a chiral auxiliary. Using only two equivalents of allyl bromide, excellent yields and very good to excellent enantioselectivities are obtained. To our knowledge, the enantioselectivities reported herein are the highest obtained for indium-promoted allylations of carbonyl compounds.     

First total synthesis of (±)-epocarbazolin A and epocarbazolin B, and asymmetric synthesis of (−)-epocarbazolin A via Shi epoxidation

Epoxidation of the trisilyl-protected carbazomadurins A and B with dimethyldioxirane followed by desilylation provides a simple route to racemic epocarbazolin A and a non-diastereoselective access to epocarbazolin B. The Shi epoxidation has been applied to an asymmetric synthesis of the non-natural (−)-epocarbazolin A.     

Enantioselective synthesis of 2-alkyl-2-aryl cyclopentanones by asymmetric epoxidation of tetrasubstituted cyclobutylidene olefins and epoxide rearrangement

This letter describes a highly enantioselective epoxidation of tetrasubstituted benzylidenecyclobutanes using glucose-derived ketone as catalyst and oxone as oxidant. The Et₂AlCl promoted rearrangement of the resulting epoxides provides 2-alkyl-2-aryl cyclopentanones with high ees.     

Asymmetric synthesis of (+)-cardiobutanolide

A formal total synthesis of (+)-cardiobutanolide has been accomplished from d-glucose, a readily available precursor.     

Enantiodivergent synthesis of (−)-methylenolactocin and (+)-methylenolactocin from d-mannitol

An enantiodivergent synthesis of both enantiomers of methylenolactocin is described through stereocontrolled addition of n-pentyl magnesium bromide to two d-mannitol-derived diastereomerically related aldehydes having an α-chiral center with a β hetero atom.     

Achiral auxiliary-assisted chiral transfer via microwave-accelerated aza-Claisen rearrangement: a short synthesis of (+)-1-hydroxyquinolizidinone

A short and efficient synthesis of (+)-1-hydroxyquinolizidinone as an advanced core intermediate for the syntheses of (+)-epiquinamide, (+)-homopumiliotoxin, and (+)-lupinine is described. The key feature of our strategy includes a sequential chiral transfer using an achiral phenylsulfide auxiliary via microwave-accelerated aza-Claisen rearrangement of the unexplored N-thiophenoxyacetyl-α-vinyl piperidine substrate and the oxone-induced transannulation.     

A highly efficient enantioselective synthesis of 2-methyl chromans via four sequential palladium-catalyzed reactions

An enantioselective synthesis of substituted 2-methyl chromans was accomplished in four steps using four sequential Pd-catalyzed reactions. A study of the key palladium-catalyzed regioselective aryl ether ring formation of two different substrates was also carried out to better understand the factors which affect the selectivity of the reaction.