Xinfu Pan

A Novel Prins Cyclization through Benzylic/Allylic C-H Activation

A step-economic method to construct the tetrahydropyran ring, involving sequential benzylic/allylic C-H bond activation via DDQ oxidation and nucleophilic attack of an unactivated olefin, is described. The equatorial-trisubstituted Prins products are obtained from benzyl and allyl homoallylic ethers with high yield and stereochemical fidelity.

Application of a domino Friedel-Crafts acylation/alkylation reaction to the formal syntheses of (+/-)-taiwaniaquinol B and (+/-)-dichroanone.

An efficient acid-promoted domino Friedel-Crafts (FC) acylation/alkylation reaction has been developed for the construction of the core 6,5,6-ABC tricyclic skeleton of taiwaniaquinoids. The formal total syntheses of diterpenoids (+/-)-taiwaniaquinol B and (+/-)-dichroanone based on this strategy have been achieved.

Concise total synthesis of (+)-aspergillide B.

An efficient total synthesis of (+)-aspergillide B has been achieved, which features the C-glycosylation reaction for constructing the 2,6-trans-substituted pyran core, a highly effective four-step sequence without purification to produce the key intermediate 13 and an advantegous E-selective Julia-Kocienski olefination on a highly elaborate substrate. The synthesis confirmed the revised structure of aspergillide B by Uenishi.

The synthesis of l-(+)-homophenylalanine hydrochloride

Abstract l -(+)-Homophenylalanine hydrochloride was synthesized from N-phthaloyl- l -(−)-asparitc anhydride 2 in three steps in 55% overall yield with 99% ee.

Synthesis of C2-symmetrical bis-β-amino alcohols and their application in the enantioselective addition of diethylzinc to aldehydes

Abstract The C 2 -symmetrical bis-β-amino alcohols 1 – 6 were prepared and especially attention is focused on bridges, which link the two β-amino alcohol units. These ligands have been applied as chiral catalysts in the asymmetric addition of diethylzinc to aldehydes. sec -Alcohols have been obtained in good yields with up to 95.4% enantiomeric excess.

Synthesis of C-7 oxidized abietane diterpenes from racemic ferruginyl methyl ether

A series of naturally occurring C-7 oxidized abietane diterpenes have been synthesized from racemic ferruginyl methyl ether in high yields. 6-Hydroxyl-5,6-dehydrosugiol (7) can be converted into stable xanthoperol (12) using high temperature. Among the products, the structures of sugiyl methyl ether (2) and 6(-hydroxysugiyl methyl ether (8) were determined by X-ray analysis.

A Modification of the Knorr Oxidative Coupling Method for Preparation of 1,4-Diketones

Abstract The oxidative coupling of β-keto esters has been achieved in good yield using NaOEt / 12.

First enantioselective synthesis of daphneticin and its regioisomer

An enantioselective total synthesis of chiral daphneticin and its regioisomer is reported for the first time.

Reduction with Metal Borohydride-Transition Metal Salt System. I. Reduction of Aromatic Nitro Compounds with Potassium Borohydride-Copper(I) Chloride

Abstract Upon treatment with potassium borohydride-copper(I) chloride, aromatic nitro compounds afforded cleanly primary amines in high yields. Similarly, nitroso-, azoxy- and azobenzene were reduced by the same reagent system to give aniline.

An efficient method for construction of the angularly fused 6,3,5-tricyclic skeleton of mycorrhizin A and its analogues.

The angularly fused 6,3,5-tricyclic system is readily generated via a cascade cyclization under acid promotion. The reaction proceeds at room temperature with high stereochemical fidelity from the electrophilic center of the epoxide to the cyclopropane product. This methodology provides a potentially useful approach for the synthesis of mycorrhizin A and its analogues.