Total synthesis of racemic,natural (+) and unnatural (−) scorzocreticin

The first total synthesis of racemic scorzocreticin and its pure enantiomers is described from readily available 3,5-dihydroxybenzoic acid. The key steps include Wittig olefination, asymmetric Me-CBS (Corey–Bakshi–Shibata) oxazaborolidine reduction, and improved Pd-catalyzed intramolecular lactonization reactions. Both the (S)-natural and (R)-unnatural enantiomers of scorzocreticin have been synthesized in excellent enantioselectivities (>99% and 99% ee, respectively). In addition, 1,10-phenanthroline, a bidentate N-ligand was employed in palladium-catalyzed intramolecular carbonylation/lactonization reaction for the construction of 3,4-dihydroisocoumarin ring.     

The second generation synthesis of (+)-pseudodeflectusin

The second generation synthesis of (+)-pseudodeflectusin (1), a potential antitumor agent, has been achieved. The key synthetic step is the cascade reaction involving Diels-Alder reaction, lactonization, and decarboxylation to give cycloadduct 6 with complete regioselectivity in good yield. We found that NaH is the best base to facilitate the Diels-Alder reaction of hydroxypyrone 7 with alkyne 8. The present synthetic route enables the total synthesis of (+)-1 in only five-steps from the known compounds 7 and 8.     

Enantioselective syntheses of bioactive epoxyquinone natural products (+)-harveynone and (−)-asperpentyn

Stereo- and enantioselective syntheses of (+)-harveynone and (−)-asperpentyn are reported.     

Total synthesis of (+)-spiculoic acid A

The total synthesis of natural (+)-spiculoic acid A, a new cytotoxic marine natural product of polyketide origin, has been accomplished for the first time. The key step of the total synthesis was a stereoselective and high-yielding intramolecular Diels-Alder reaction of a highly functionalized (E,E,E)-2,7,9-dodecanal derivative for the construction of the core tetrahydroindan-2-one skeleton.     

Total synthesis of (−)-muricatacin

A total synthesis of (−)-muricatacin has been achieved using a commercially available starting material and our furan approach to oxacyclic systems, the proven scope of which is thus broadened.     

Total synthesis of (+)-epiepoformin, (+)-epiepoxydon and (+)-bromoxone employing a useful chiral building block, ethyl (1R,2S)-5,5-ethylenedioxy-2-hydroxycyclohexanecarboxylate

Enantioselective total synthesis of (+)-epiepoformin 1, (+)-epiepoxydon 2 and (+)-bromoxone 3 using a chiral building block, ethyl (1R,2S)-5,5-ethylenedioxy-2-hydroxycyclo- hexanecarboxylate 6, is described. Since the synthesis afforded intermediates 18, 2 and 25, it accomplished a formal synthesis of (−)-theobroxide 19, (−)-phyllostine 22, (+)-herveynone 27 and (−)-asperpentyn 28. The usefulness of 6 for the synthesis of natural epoxycyclohexene derivatives was demonstrated.     

Total synthesis of (−)-petrosiol E

(−)-Petrosiol E, a metabolite of sponge Petrosia strongylata, has been synthesized in 32% overall yield from cheap natural d-xylose in 10 steps. Our strategy provides an efficient way for the total synthesis of other petrosiol members, featuring the three contiguous stereogenic centers are easily constructed from d-xylose chiral template.     

Total synthesis of (−)-centrolobine

Stereoselective synthesis of (−)-centrolobine, an anti-Leishmania agent, was accomplished via an intramolecular Barbier-type reaction of iodo-ester with n- or t-butyllithium followed by Lewis acid-promoted Et₃SiH reduction of the resulting hemiacetal.     

Total synthesis of (−)-nakadomarin A: alkyne ring-closing metathesis

A 13-step, highly stereoselective synthesis of (−)-nakadomarin A has been achieved using the combination of a bifunctional organocatalyst controlled Michael addition, a nitro-Mannich/lactamization cascade, an alkyne ring-closing metathesis/syn-reduction, and furan/iminium ion cyclization/reduction as key steps.     

Total synthesis of (−)-Englerin A

A novel and efficient total synthesis of Englerin A is reported. The synthesis featured an intramolecular olefin metathesis ring closure reaction and a highly stereoselective oxygen bridge formation induced by an iodonium ion. This strategy can be used for the synthesis of natural products Englerin A and Englerin B and can provide flexibility in the preparation of various 9-substituted analogues of Englerin A for further structure–activity relationship studies.     

Stereocontrolled total synthesis of (−)-aspidophytine

The enantioselective stereocontrolled total synthesis of aspidophytine is described. The key indole intermediate was prepared by radical cyclization of 2-alkenylphenylisocyanide, followed by Sonogashira-coupling with a highly functionalized terminal acetylene. The 11-membered cyclic amine, a precursor for the formation of the aspidosperma skeleton, was synthesized using nitrobenzenesulfonamide chemistry. After construction of the pentacyclic skeleton, the lactone ring was formed to complete the total synthesis.     

Total synthesis of (−)-baconipyrone C

A highly stereoselective asymmetric total synthesis of marine polypropionate (−)-baconipyrone C has been achieved. Utilization of desymmetrization technique to create five stereogenic centres, Sharpless epoxidation, Gilman's reaction and resolution of methyl group using enzyme PS-C is the highlight of the synthesis.     

Stereoselective syntheses of (−)-chloramphenicol and (+)-thiamphenicol

Chloramphenicol and thiamphenicol have been enantioselectively synthesized using an asymmetric halohydrin reaction as a key step. In particular, halomethoxylation reaction was used, where O-methyl functions as a hydroxyl protecting group and eliminates an additional protection step.