Synthesis and absolute configuration of brevione B, an allelochemical isolated from Penicillium sp.

Breviones A-E (1-5), allelochemicals isolated from Penicillium brevicompactum Dierckx, are structurally unique diterpenoid derivatives. The first synthesis of both enantiomers of brevione B (2) was accomplished by employing the double S_N2′-type tandem reaction as a key step, and the absolute configuration of the naturally occurring 2 was established.     

A concise synthesis of (±)-pseudodeflectusin, an antitumor isochroman derivative isolated from Aspergillus sp.

A novel and concise synthesis of (±)-pseudodeflectusin (1), an antitumor isochroman derivative isolated from the culture broth of Aspergillus pseudodeflectus, was accomplished by starting from 4-(tert-butyldimethylsilyloxy)-1-pentyne (3) and diethyl 3-oxopentanedicarboxylate (5).     

The first total synthesis of (±)-zenkequinone B

The first total synthesis of tetrahydrobenzo[a]anthraquinone natural product (±)-zenkequinone B (1) is reported. The key step involves the TiCl₄-promoted intramolecular cyclization of 4-aryl-2-hydroxybutanal diethyl acetal 4 to give compound 3. The total synthesis of (±)-zenekequinone B (1) has been accomplished in five steps from readily available 2-(chloromethyl)-9,10-dimethoxyanthracene (5) in 40.3% overall yield.     

Improved total synthesis of (±)-trans-dihydronarciclasine, devised for large-scale preparation

New synthetic route to (±)-trans-dihydronarciclasine, more suitable for a large-scale preparation, has been devised with the early stage incorporation of ester functionality for direct assembly of the B-ring lactam.     

The first total synthesis of (±)-laurokamurene B

The first total synthesis of the rearranged aromatic sesquiterpene (±)-laurokamurene B, isolated from the Chinese red alga Laurencia okamurai Yamada, has been accomplished, confirming the structure of the natural product. A combination of Ireland-Claisen rearrangement and ring-closing metathesis was employed as key reactions.     

The first total synthesis of a bioactive metabolite, a spirobenzofuran isolated from the fungi Acremonium sp. HKI 0230

The first total synthesis of a bioactive metabolite, isolated from the fungi Acremonium sp. HKI 0230, containing a cyclopentaspirobenzofuran carbon framework, employing an Ireland ester Claisen rearrangement and RCM reaction based strategy has been accomplished.     

Formal synthesis of (±)-indolizidine 209B

A new method for the synthesis of cis-C-8 methylated indolizidines and quinolizidines has been developed. Straightforward transformations including an isomerization to the trans configuration led to a formal synthesis of (±)-indolizidine 209B.     

Total synthesis of (±)-hyrtiazepine

The total synthesis of the azepinoindole alkaloid, (±)-hyrtiazepine, was achieved. Construction of the azepinoindole core structure was carried out by C-4 selective α-hydroxyalkylation of 5-hydroxyindole, introduction of serine at C-3 of the indole moiety, and intramolecular imination.     

Total synthesis of (±)-antofine

An efficient preparation of (±)-antofine is described. The main steps involved in this synthesis are the Horner–Wadsworth–Emmons reaction, the intramolecular Schmidt reaction of an azido aldehyde, and the one-pot deprotection of the N-formyl group, followed by Pictet–Spengler cyclization. The asymmetric hydrogenation of the trisubstituted α,β-unsaturated ester is also explored, however only moderate enantio-control (55% ee) is obtained. Finally, (±)-antofine is prepared in six steps from the phenanthryl aldehyde 5 with an overall yield of 35%.     

A concise synthesis of anti-viral agent F-ddA, starting from (S)-dihydro-5-(hydroxymethyl)-2(3H)-furanone

Anti-HIV agent β-F-ddA (1) has been synthesized starting from readily available non-sugar, (S)-(+)-Dihydro-5-(hydroxymethyl)-2-(3H)-furanone (4). A highly syn-stereoselective fluorination of the hydroxy lactone 2 generates the key intermediate fluorolactone 5 in a short and concise synthetic sequence. Reduction of 5 followed by bromination generates the aglycon which is glycosylated to generate F-ddA by amination and deprotection. Steric bulk of the 5-protecting group has minimal effect on the steric course of glycosylation.     

The first total synthesis of (±)-lagopodin A

The first total synthesis of (±)-lagopodin A and a formal total synthesis of enokipodins A and B is described. The requisite precursors containing two vicinal quaternary carbon atoms were assembled employing Claisen rearrangement and an RCM reaction as key steps starting from 2,5-dimethoxy-4-methylacetophenone.     

Dibromomethane as one-carbon source in organic synthesis: total synthesis of (±)-canadensolide

A diastereoselective total synthesis of (±)-canadensolide is described. The key step is to introduce the α-methylene group by the ozonolysis of mono-substituted alkenes followed by reaction with a preheated mixture of CH₂Br₂-Et₂NH.     

The first total synthesis of acutifolone A, a pinguisane-type sesquiterpenoid isolated from the Japanese liverwort Porella acutifolia subsp. tosana

The first total synthesis of acutifolone A, a sesquiterpenoid carrying the bicyclo[4.3.0]nonane structure 1, was successfully achieved from the intermediate 6 produced by the intramolecular Diels-Alder reaction.     

The first total synthesis and absolute stereochemistry of plakortone G from the Jamaican sponge Plakortis sp.

Total synthesis of plakortone G (1), a secondary metabolite of the Jamaican sponge Plakortis sp., was successfully achieved. The absolute configuration of this molecule was determined by comparison of the synthetic diastereomers with reported data to possess the (4R,8R)-configuration 14.     

First synthesis of (±)-sorgomol, the germination stimulant for root parasitic weeds isolated from Sorghum bicolor

Sorgomol, isolated from Sorghum bicolor, is the germination stimulant for seeds of root parasitic weeds. The first synthesis of (±)-sorgomol has been achieved by starting from ethyl 2-oxocyclohexanecarboxylate.     

Total synthesis of (±)-herbertenediol

A formal total synthesis of the sesquiterpene (±)-herbertenediol and its dimers mastigophorenes A-D has been accomplished, starting from vanillin via 2,3-dimethoxy-5-methylbenzaldehyde. A combination of Claisen rearrangement and ring-closing metathesis reactions were employed for the generation of the two vicinal quaternary carbons on a cyclopentane ring.     

The first total synthesis of (R)-convolutamydine A

The first total synthesis of (R)-convolutamydine A has been achieved by the organocatalytic addition of acetone to 4,6-dibromoisatin. The absolute configuration was determined by single crystal X-ray diffraction. DFT studies were used to model the transition states for the aldol reaction and equilibrium geometries of the post-aldol reaction intermediates. The DFT study revealed that the aldol bond forming reaction was considerably endothermic.     

Studies on novel macrocyclization methods of cembrane-type diterpenoids: a Stille cyclization approach to (±)-isocembrene

An efficient total synthesis of (±)-isocembrene via an intramolecular Stille cross-coupling reaction is described. A novel strategy towards the 1,3-diene-based cembrane-type macrocyclic diterpenoids has been realized.     

Synthetic studies on basidifferquinones: the first synthesis of (±)-basidifferquinone C

Basidifferquinones, isolated from Streptomyces sp., are potent inducers for fruiting-body formation of a basidiomycete Polyporus arcularius. Construction of the basic framework of basidifferquinones and the first synthesis of (±)-basidifferquinone C were accomplished by starting from 3,5-dihydroxy-2-naphthoic acid.     

A stereocontrolled total synthesis of methyl (±)-O-methylpodocarpate

A stereocontrolled total synthesis of methyl (±)-O-methyl podocarpate (4) has been successfully accomplished using the trans-fused diester 21 as a key intermediate. Intramolecular Michael reaction of the enone-diester 18 afforded the cis-fused keto-diester 19 in high yield which was stereoselectively converted into 21 via the enone 20.