Total synthesis of (±)-clavam-2-carboxylic acid

Racemic clavam-2-carboxylic acid has been obtained by a six-stepsynthesis from readily available starting materials.     

Stereocontrolled synthesis of D-α-hydroxy carboxylic acid from L-amino acids

Optically active D-α-hydroxy carboxylic acids are obtained from L-amino acids via L-α-halocarboxylic acids and their stereoselective reaction with cesium p-nitrobenzoate.     

Stereocontrolled synthesis of substituted bicyclic ethers through oxy-Favorskii rearrangement: total synthesis of (±)-communiol E

The potential of the oxy-Favorskii rearrangement to form branched cis-fused bicyclic ethers was explored. Both tertiary and quaternary centers were constructed in highly stereospecific manners. Methanol and primary amines were effective nucleophiles for the rearrangement. The total synthesis of (±)-communiol E was achieved based on this method.     

First total synthesis of (±)-trolline

Trolline, a new bioactive alkaloid was isolated in 2004. We reported herein the first total synthesis of (±)-trolline, in two steps and 18.0% overall yield.     

Stereocontrolled total synthesis of the macrocyclic lactone (−)-aspicilin

The essential features of the enantiocontrolled total synthesis of (−)-aspicilin are the strategic use of the photochemical rearrangement of α,β-epoxy diazomethyl ketones to 4-hydroxyalkenoates (Scheme 1) and the stereochemical control of the Sharpless epoxidation, α,ω functionalization of an alkynol using potassium 3-aminopropylamine (KAPA) as acetylene zipper, coupling between C₇ and C₈ by means of a Wittig reaction and lactonization by using 2,6-dichlorobenzoyl chloride.     

A highly diastereoselective total synthesis of (±)-heritonin and (±)-heritol

A highly diastereoselective synthesis of heritol and heritonin by intramolecular cyclization on a preformed sensitive butenolide functionality is described.     

First total synthesis of (±)-puyanin and (±)-4'-O-methylbonannione

<正>A facile approach for the first total synthesis of two naturally occurring geranylated flavonoids,(±)-puyanin 1 and(±)-4'-O- methylbonannione 2 has been obtained with total yield 27%and 21%,respectively.The key steps were regioselective cyclization of geranylated trihydroxychalcone and regioselective geranylation of 2,4,6-trihydroxyacetophenone.     

A novel and efficient total synthesis of(±)-Cembrene-A

(±)-Cembrene-A,a highly active scent-trail pheromone,was first isolated from thetermite(Nasutitermes exitiosus)and its structure was established by using chemical and spectralmethods,Afterwards,it was also found in some plants and soft corals.In view of itsbiological activity,some total syntheses have been reported.It was reported that its dl-form showed the same order of activity as that of the natural pheromone,In previous work,     

Methylenecyclohexane annulation. Total synthesis of (±)-axamide-1, (±)-axisonitrile-1, and the corresponding C-10 epimers

Conjugate addition of 2-(5-chloro-1-pentenyl)magnesium bromide (12) to 2-methyl-2-cyclopenten-1-one (6), followed by intramolecular alkylation of the resultant product, afforded (85%) the bicyclic ketone 7, which was transformed (77%) into the enone 16. Titanium tetrachloride-catalyzed conjugate addition of 3-methyl-1,1-bis(trimethylsiloxy)-1-butene to 16 gave (93%) a 3:2 mixture of the keto acids 20 and 21, which were separated. Compound 20, the stereochemistry of which was confirmed by a single-crystal X-ray analysis, was converted into (±)-axamide-1 (1) and (±)-axisonitrile-1 (2), while 21 was transformed into the corresponding C-10 epimers 8 and 9, respectively.     

Total synthesis of (±)-sterpuric acid

The unusual sesquiterpenoid fungal metabolite sterpuric acid (1) has been assembled in 11 steps and 11% overall yield from the readily available vinyl sulfone 2.     

Concise total synthesis of (±)-dasyscyphin D

The first and efficient total synthesis of (±)-dasyscyphin D was achieved in 9 steps with 22.6% overall yield. The key steps involved a PtCl(2)-catalyzed pentannulation reaction and acid-catalyzed double Robinson annulations.     

Stereoselective total synthesis of (±)-peribysin E

Radical cyclization of iodoketone 3 afforded cis-hydrindanone 8. Compound 8 was converted into key intermediate 5 via conventional transformations. Annulation of a spiro-lactal unit to 5 was pursued with three different approaches. In the first approach, radical cyclization of propargyl ester 17 provided spiro-lactone 18 with an undesired stereochemistry. Attempts to invert the stereochemistry at the spiro-center via retro-aldol and aldol condensation of compound 20 failed. In the second approach, key intermediate 5 was transformed into 23. Acylation of compound 23 gave 24 as a single diastereomer with the desired stereochemistry but in low yield. NBS bromination of 24 followed by lactone formation gave 26 in low yield. Alternatively, allylic oxidation of 24 with SeO(2) followed by lactonization gave 26 also in low yield. Finally, a third approach employing a semipinacol-type rearrangement of epoxy-alcohol 33 gave aldehyde 34 with the desired stereochemistry. Treatment of compound 34 with HCl in MeOH effected spiro-lactal formation and provided (±)-peribysin E. The overall yield of our synthesis is 3.2% from 2-methylcyclohenen-1-one.     

A concise total synthesis of (±)-minfiensine

A concise total synthesis of (±)-minfiensine using all conventional methods and starting from commercial materials has been completed. The synthesis features a Fischer indole synthesis, a Heck alkylation of an intermediate ketone enolate, conversion of a ketone carbonyl into an epoxide, and transformation of the latter into an allylic alcohol.     

The total synthesis of (±)-sanggenol F

A concise and efficient total synthesis of sanggenol F (1) in racemic form has been completed via a sequence of 15 steps with an overall yield of 3.1%, starting from commercially available 2,4,6-trihydroxyacetophenone. Meanwhile, a semisynthesis of sanggenol F racemate has also been achieved in 11.1% overall yield via 7 steps with naturally-occurring morin (2) as the starting material. One step and a stepwise approach were employed to construct the two prenyl side chains at 2- and 6-positions by Claisen rearrangement reaction.     

Improved total synthesis of (±)-Tetragocarbone A

Stereoselective total synthesis of (±)-tetragocarbone A isolated from the propolis of an Australian stingless bee, Tetragonula carbonaria, has been developed by focusing on the latent symmetry of 1. The requisite 1R*, 3R*, 6S* stereogenic centers were selectively installed by hydroxy group directing reactions including the late stage desymmetrization of the 1,3-diketone. The target natural product was successfully prepared in 12 steps from phloroglucinol on 300 mg.     

First total synthesis of (±)-abyssinoflavanone V

The total synthesis of (±)-abyssinoflavanone V was first achieved through C-prenylation, selective protection of phenolic hydroxyl group, aldol condensation, cyclization and deprotection starting from cheap 4-hydroxybenzaldehyde and 2,4,6-trihydroxyacetophenone, with total yield 24%. All structures of new compounds were confirmed by IR, 1H NMR and MS.