Formal total synthesis of (±)-magellanine

Formal total synthesis of magellanine is described. Key features in the synthesis were stereoselective Ireland-Claisen rearrangement and intramolecular Pauson-Khand reaction of exo-cyclic enynes.     

First total synthesis of (±)-adunctin B

The first total synthesis of (±)-adunctin B (1), a natural product isolated from Piper aduncum (Piperaceae) and having antibacterial activity, was achieved in 1.26% overall yield in 15 steps from 5,7-dimethoxycoumarin-3-carboxylate (8).     

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.     

A novel synthetic route for the total synthesis of (±)-uleine

In this study, a new synthetic route for the total synthesis of (±)-uleine is described. The important step in the synthesis of this alkaloid consists of an intramolecular cyclization of the D ring of the azocino[4,3-b]indole skeleton. Reduction of (N-methyl){3-β-ethyl-4-oxo-2,3,4,9-tetrahydrospiro[1H-carbazole-1,2′(1,3)dithiolane]-2-yl}-2-acetamide with borane yielded the corresponding (N-methyl){3-β-ethyl-4-hydroxy-2,3,4,9-tetrahydrospiro[1H-carbazole-1,2′(1,3)dithiolane]-2-yl}-2-acetamide, which underwent acid-catalyzed ring closure to produce azocino[4,3-b]indole core. Finally, the synthesis of (±)-uleine was completed through several steps from the azocino[4,3-b]indole core.     

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.     

Total synthesis of (±)-brazilin and formal synthesis of (±)-brazilein, (±)-brazilide A using m-CPBA

Total synthesis of (±)-brazilin has been accomplished. m-CPBA epoxidation of allyl alcohol 10 and epoxy opening reaction mediated by m-chlorobenzoic acid, formed in situ as a byproduct, gave advanced intermediate diol 14. O-alkylation and cyclization gave phenol 6 which enabled the formal synthesis of (±)-brazilein and (±)-brazilide A.     

Total synthesis of nothapodytine B and (±)-mappicine

A novel, efficient total synthesis of the naturally occurring antiviral nothapodytine B (2, mappicine ketone) is reported. The approach is based on the successful implementation of the Johnson orthoester rearrangement of allylic alcohol 7 for assembly of a pyridone D ring precursor with the necessary functionalities. Nothapodytine B is converted into mappicine 3 by NaBH₄ reduction.     

First total synthesis of(±)-sepicanin A

<正>A facile approach for the first total synthesis of naturally occurring geranylated flavanoids sepicanin A has been obtained with total yield 16%starting from 2,4,6-trihydroxyacetophenone after four steps.The key step was the protic acids(HCl or p-TsOH)-catalyzed benzopyrone formation in a protic polar solvent by deprotection and cycUzation of chalcone in one step.     

The first total synthesis of trichostatin D

Trichostatin D and 6-epi-trichostatin D have been stereoselectively synthesized through a remote stereoinduction with a chiral vinylketene silyl N,O-acetal and glycosylation of hydroxyimide under Mitsunobu conditions.     

A simple and efficient total synthesis of (±)-danshexinkun A, a bioactive diterpenoid from Salvia miltiorrhiza

An efficient 12-step route for the synthesis of the diterpenoid quinone (±)-danshexinkun A in 23% overall yield from the corresponding highly substituted stilbene using a photocyclization strategy is described.     

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.     

The first total synthesis of telephiose A

The first total synthesis of telephiose A (1), a novel trisaccharide ester having two acetyl groups and two benzoyl groups, was achieved by using glucosyl donor 6 and disaccharide acceptor 12. The crucial key step was the stereoselective construction of the β-d-glucosidic linkage featuring the neighboring group participation of the 2-O-N-phenylcarbamoyl group (of donor 6), which can be selectively deprotected in the presence of acetyl and benzoyl groups. Donor 6 was prepared from d-glucose in eight steps (33% yield), whereas acceptor 12 was prepared from sucrose in six steps (35% yield). Precursors 6 and 12 were reacted in subsequent reactions (five steps) to afford 1 in 22% yield.     

A new approach to the C28 fatty acid chain of the marine natural products schulzeines B and C: a concise diastereoselective total synthesis of(−)-schulzeine B

An enantioselective approach to the C₂₈ fatty acid chain of the marine natural products schulzeines B and C was established based on the l-tartaric acid derived C₄ chiron 11 via successive 1,4-bis-chain elongation reactions and catalytic asymmetric hydrogenation. The chiral tricyclic core 8 was constructed via a diastereoselective Pictet-Spengler cyclization reaction (dr = 89:11) of the l-glutamic acid derived precursor 13. On this basis, a concise total synthesis of (−)-schulzeine B (5) was disclosed.     

Total synthesis of (±)-lantalucratins A and B by CAN-mediated oxidative cyclization

The first total synthesis of (±)-lantalucratins A and B is described. Introduction of an alkyl side chain at the 6-position was proceeded by directed ortho-lithiation and subsequent alkylation reaction to afford 6-alkyl-5,7,8-trimethoxy-1-naphthol as a synthetically important intermediate for (±)-lantalucratins A and B in excellent yield with complete regioselectivity. The 1,2-naphthoquinone fused five-membered cyclic ether framework was constructed directly from 3-hydroxyalkyl-naphthalenes by oxidative intramolecular cyclization reaction with diammonium cerium(IV) nitrate. (±)-Lantalucratins A and B were obtained in 69% and 45% overall yields, respectively.     

Studies on the total synthesis of tenuifoliside B

An efficient synthesis of tenuifoliside B, which shows potential cognitive improvement and cerebral protective effects that may be further developed to become an anti-AD lead compound, has been developed starting from commercial available starting materials. Regioselective introductions of acyl groups to the OH-3′ and OH-6 of sucrose play the key steps by metal chelate-directed acylation and Mitsunobu esterification, respectively.     

The first total synthesis of (±)-4-methoxydecanoic acid: a novel antifungal fatty acid

The hitherto unknown (±)-4-methoxydecanoic acid was synthesized in six steps and in 25% overall yield starting from commercially available 4-penten-1-ol. The title compound demonstrated 17-fold higher antifungal activity (MIC = 1.5 mM) against Candida albicans ATCC 60193 and Cryptococcus neoformans ATCC 66031 when compared to unsubstituted n-decanoic acid. Our results demonstrate that mid-chain methoxylation appears to be a viable strategy for increasing the fungitoxicity of fatty acids.     

Total synthesis of (±)-megistophylline I

(±)-Megistophylline I (1), carrying a dienone residue in the acridone framework, was synthesized using the Claisen rearrangement to introduce a prenyl group as a key step.     

Syntheses of (±)-9-epi-hederacine A and (±)-9-epi-hederacine B

Racemic syntheses of 9-epi-hederacine A and 9-epi-hederacine B have been achieved. Key transformations include a transannular hemiaminal formation for construction of the azabicyclo[3.2.1]octane core fused to a cyclopentane ring.     

以淀粉溶液为催化剂锅三组分法合成四氢苯并[b]吡喃和3,4-二氢吡喃并[c]苯并吡喃衍生物简

Tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives were synthesized via a one-pot three-component condensation of aromatic aldehydes with malononitrile and dimedone or 4-hydroxycoumarin in excellent yields in the presence of starch solution as a highly efficient homogenous catalyst. The use of a nontoxic and biodegradable catalyst, simple work-up procedure, and short reaction time are advantages of this method.     

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.