A Short Synthesis of (±)-Matrine

Three different radical reactions were used in a short total synthesis of (±)-matrine ( 1 ). Two of the four six-membered rings and four new bonds were created in one radical cascade involving intermolecular addition followed by two successive cyclizations and transfer of a xanthate group.     

A Short Convergent Synthesis of (±) Patulolide A

A short, convergent synthesis of (±) patulolide A, a 12-membered macrolide with high antifungal activities is hereby reported. It has been achieved in 10 steps from 1-bromopentanal and 4-hydroxypent-1-yne.     

A Short Synthesis of Benzomorphane Analgesics (±)-Metazocine and (±)-Phenazocine

A three step synthesis of (±)-metazocine and (±)-phenazocine starting with 3,4-lutidine is described. The key step involves Lewis acid promoted lithiation/electrophilic substitution reaction of N-alkyl-3,4-dimethyl-1,2,5,6- tetrahydropyridine.     

A Total Synthesis of (±)-α-Chamigrene-3-one

Thephotocycloadditionofmethyl2,4-dioxopentanoate1toalkenesorconjugatedolefins2regioselectivelygavethecycloadduct3(Schemel).ThisreactioncouldconvenientlybeusedtoconstructthebasicframeworkofvariousnatUraIlyoccutringchamigran-tyPespirosesquiterPenes,suchasa-chamigrene",6-chamigrene:=,andaseriesofrelatedhaIogenatedderivativesd.The(i)-Q-Chamigrene-3-onewasanewmemberofthisfamilyandwasrecentlyisolatedfromMarchantiapolymorPha".whichpossessedthestrUctUreofasyntheticintermediate,1-methoxycarbonyl-5,…     

A Short,Efficient and Stereos Elective Synthesis of (±)-Recifeiolide

The synthesis of macrolides¹ is currently under intensive investigations because of their diverse biological and physiological activities. The recent developments in their synthetic strategies made the task easier for synthesis of several naturally occurring rnacrolides.     

Total Synthesis of (±)-Calanolide A

The total synthesis of (±)-Calanolide A, incorporating a ring-forming sequence different from previous procedures, is described.     

Total Synthesis of (±)-Celaphanol A

Celaphanol A was a diterpene isolated from the stems of Celastrus stephanotifolius1, which have been the subject of continued and growing interest, due to the range of biological activities shown by many members of this family2. Some have been used in traditional medicine3 or as a stimulant4 from ancient times. In order to further study the relationship between the structure and biological activity of the diterpene compound and as an extension of diterpenoid synthesis in our laboratory5, 6, …     

A Total Synthesis of (±)-Trichodiene

Trichodiene (1), a sesquiterpene hydrocarbon, was isolated from the extract of mycelium of Trichothecium roseum. The structure of trichodiene (1) was elucidated by Nozoe and Machida in 1970 via degradation and spectroscopy.¹ Trichodiene (1) has been shown to be the biogenetic precursor of the trichothecane family of sesquiterpenoids as characterized by the cytotoxic fungal metabolite (-)-trichodermin (2).^2,3 The structure and absolute stereochemistry of (-)-trichodermin (2) were determined by X-ray diffraction and, therefore, the structure and absolute stereochemistry of trichodiene (1) are now firmly established.⁴ We wish to report a total synthesis of (±)-trichodiene (1) via previously reported lactone 3.^5,6     

Synthesis of (±)-chamobtusin A by a presumed biomimetic aza-cyclization

A total synthesis of (±)-chamobtusin A has been accomplished on the basis of our presumed biosynthetic pathway: the imine formation of keto aldehyde followed by intramolecular aza-Michael addition.     

Synthesis of (±)-7-hydroxylycopodine

A six step synthesis of (±)-7-hydroxylycopodine has been achieved in 5% overall yield. In the key step, a Prins cyclization of a bicyclic keto alkyne in 60% H(2)SO(4) forms a tricyclic dihydroxy amino ketone.     

Synthesis of (±)-7-hydroxylycopodine

A seven-step synthesis of (±)-7-hydroxylycopodine that proceeds in 5% overall yield has been achieved. The key step is a Prins reaction in 60% sulfuric acid that gave the key tricyclic intermediate with complete control of the ring fusion stereochemistry. A one-pot procedure orthogonally protected the primary alcohol as an acetate and the tertiary alcohol as a methylthiomethyl ether. The resulting product was converted to 7-hydroxydehydrolycopodine by heating with KO-t-Bu and benzophenone in benzene followed by acidic workup. During unsuccessful attempts to make optically pure starting material, we observed the selective Pt-catalyzed hydrogenation of the 5-phenyl group of a 4,5-diphenyloxazolidine under acidic conditions and the Pt-catalyzed isomerization of the oxazolidine to an amide under neutral conditions. In attempts to hydroxylate the starting material so that we could adapt this synthesis to the preparation of (±)-7,8-dihydroxylycopodine (sauroine) we observed the novel oxidation of a bicyclic vinylogous amide to a keto pyridine with Mn(OAc)(3) and to an amino phenol with KHMDS and oxygen.     

Biomimetic Total Synthesis of (±)-Homodimericin A

A biomimetic total synthesis of racemic homodimericin A was achieved in seven steps, including two cascade reactions. Aqueous buffer solutions are found to help both the oxidative dimerization cascade and the intramolecular Diels–Alder cascade. This synthetic sequence validates key steps in the biogenetic proposal of homodimericin A.     

A Novel Total Synthesis of (±)Shikonin

Shikonin 1 was a key component isolated from the traditional Chinese herbal medicine, Zicao(Lithospermum erythrorhizon Sieb.et Zucc), which possesses multiple biological activities1. There have been many synthetic routes to shikonin, however, all these ro…     

Synthesis of (±)-Altaicadispirolactone

The first synthesis of (±) Altaicadisporolactane 1 is described starting from succinic anhydride.     

Synthesis of (±) Combretastatin

Combretastatin (1) is a new plant product isolated recently by Pettit et al ¹. from the South African tree, Combretum caffrum that possesses central nervous system antineoplastic activity and is being evaluated against several of National Cancer Institute's key evaluation systems. The structure of 1 was established on the basis of its spectral properties and confirmed by X-ray analysis. However, the absolute configuration and the synthesis of 1 have not been reported so far. As combretastatin is present in the plant in only 0.0008% and the isolation technique is much tedious, there is an urgent need for the synthesis of 1 for further evaluation of its activity. This prompted us t o report the first synthesis of (±)1.     

Synthesis of (±)-Bimatoprost

A general synthetic approach has been developed for the synthesis of a key intermediate (6) that can be elaborated into several ophthalmic prostaglandins and their derivatives. Using these strategy, we have obtained (±)-bimatoprost (1) and its analog, (±)-homobimatoprost (5).     

Synthesis of (±)-zearalenone

The aliphatic portion of (±)-zearalenone has been synthesised by a new simple route starting from 2,3-dihydropyran and 2-acetyl-γ-butyrolactone by employing dithiane for C-C bond formation. The final condensation of this segment with the aromatic part and subseqnet transformations led to (±)-zearalenone.