Synthesis of (+/-)-vibralactone

Reductive alkylation of methyl 2-methoxybenzoate with prenyl bromide and hydrolysis afforded methyl 6-oxo-1-prenyl-2-cyclohexenecarboxylate. Reduction of the ketone, hydrolysis, iodolactonization, ozonolysis, and intramolecular aldol reaction provided a spiro lactone cyclopentenal. Retro-iodolactonization with activated Zn, formation of the beta-lactone, and reduction of the aldehyde completed an efficient first synthesis of (+/-)-vibralactone. No protecting groups were used except for the novel use of an iodolactone to protect both the prenyl double bond and carboxylic acid.     

增产胺及其类似物的合成

改进了２－（３，４－二氯苯氧）乙基二乙胺的制备方法。     

Synthesis of (+/-)-aculeatins A and B

The first synthesis of two new antiprotozoal and natural products was performed using concomitant deprotecting dithiane-phenolic oxidative reactions to form in one-step the 1,7-dioxadispiro[5.1.5.2]pentadecane core.     

Total Synthesis of (+/-)-Leporin A

An efficient synthesis of (+/-)-leporin A (1) has been developed using a tandem Knoevenagel condensation-inverse electron demand intramolecular hetero Diels-Alder reaction to construct the key tricyclic intermediate 3 from pyridone 5 and dienal 6 in one pot in 35% yield. Hydroxylation (71%) of 3 and methylation (77%) of the resulting hydroxypyridone 2 completed the first total synthesis of (+/-)-leporin A (1).     

Synthesis of (+/-)-brazilin using IBX

[reaction: see text] A short synthesis of (+/-)-brazilin is reported. This synthesis uses several interesting and underutilized transformations including a regioselective dirhodium-catalyzed aryl C-H insertion, a regioselective IBX phenol --> o-quinone oxidation, a tautomerization of an o-quinone to a p-quinone methide, and an intramolecular aryl cyclization with a p-quinone methide.     

Synthesis of (+/-)-phloeodictine A1

The antitumor antibiotic phloeodictine A1 (2) has been synthesized by a convergent seven-step route in 8% overall yield. The key step was the Eguchi aza-Wittig reaction of 6 to give 13 followed by a retro Diels-Alder reaction to liberate 5. Addition of 11-dodecenylmagnesium bromide to 5 to give 4b, alkylation with 18b, and deprotection completed the first synthesis of 2.     

Synthesis of (+/-)- and (-)-vibralactone and vibralactone C

Mander reductive alkylation of methyl 2-methoxybenzoate with prenyl bromide and hydrolysis of the enol ether afforded methyl 6-oxo-1-prenyl-2-cyclohexenecarboxylate. This was converted in five steps (reduction of the ketone, saponification, iodolactonization, ozonolysis, and intramolecular aldol reaction) to a spiro lactone cyclopentenal. An efficient first synthesis of (+/-)-vibralactone was completed by retro-iodolactonization with activated Zn, formation of the beta-lactone (vibralactone C), and reduction of the aldehyde. Except for the novel use of an iodolactone to protect both the prenyl double bond and carboxylic acid, no protecting groups were used. A similar sequence starting with asymmetric reductive alkylation of the (2S)-2-methoxymethoxymethylpyrrolidine amide of 2-methoxybenzoic acid with prenyl bromide afforded (-)-vibralactone confirming the absolute stereochemical assignment that was based on computational methods.     

An Efficient Synthesis of (+/-)-Narwedine and (+/-)-Galanthamine by an Improved Phenolic Oxidative Coupling

No Abstract     

Total synthesis of (+/-)-terpestacin and (+/-)-11-epi-terpestacin

The total synthesis of racemic terpestacin and 11-epi-terpestacin using the allene ether Nazarov reaction as the key step is described. All stereochemistry is derived from the stereogenic carbon atom that is formed during the Nazarov reaction.     

Formal syntheses of (+/-)-pinnaic acid and (+/-)-halichlorine

[chemical reaction: see text]. Concise formal syntheses of marine alkaloids (+/-)-pinnaic acid (1) and (+/-)-halichlorine (2) have been accomplished from a common intermediate. The syntheses illustrate the utility of selective olefin cross metathesis methodologies for the elaboration of advanced synthetic intermediates in complex molecule synthesis.     

Biomimetic synthesis of (+/-)-pinnatal and (+/-)-sterekunthal A

Concise biomimetic syntheses of the antimalarial naphthoquinones (+/-)-pinnatal and (+/-)-sterekunthal A are described.     

Total syntheses of (+/-)-montanin A and (+/-)-teuscorolide

The first total syntheses of (+/-)-montanin A and (+/-)-teuscorolide have been achieved from an advanced precursor previously developed via a Diels-Alder strategy; in the synthetic sequence, the synthesis of montanin A was first accomplished in 8 steps, from which teuscorolide was readily achieved in 2 steps by using a novel furan oxidative cyclization-retro-cyclization process as a key operation.     

Total synthesis of (+/-)-herbindole A, (+/-)-herbindole B, and (+/-)-cis-trikentrin A

Herein we describe a divergent total synthesis of the title compounds utilizing Diels-Alder reactions of monoimine quinoids, followed by cyclization of the aromatized adducts to generate the tricyclic skeletons. Elaboration to iodinated or triflated indole derivatives allows for installation of the requisite alkyl substitution via cross-coupling reactions.     

Synthesis of the tetrahydroisoquinoline alkaloid (+/-)-renieramycin G and A (+/-)-lemonomycinone analogue from a common intermediate

The total synthesis of tetrahydroisoquinoline alkaloids (+/-)-renieramycin G (4) and a lemonomycinone analogue (7) is described. A general strategy to synthesize both the mono- and bistetrahydroisoquinoline alkaloids from a common advanced intermediate, 17, is presented.     

Use of Conjugated Dienones in Cyclialkylations: The Total Syntheses of (+/-)-Barbatusol, (+/-)-Pisiferin, (+/-)-Deoxofaveline, (+/-)-Xochitlolone, and (+/-)-Faveline

Concise syntheses of five tricyclic diterpenoids are reported. The key reaction in each synthesis is a cyclialkylation of a functionalized arene with a Lewis acid-activated conjugated dienone to generate a 6,7,6-fused tricycle.     

Syntheses and anti-HIV activities of (+/-)-norcarbovir and (+/-)-norabacavir

Norcarbovir (1) and norabacavir (2), the desmethylene derivatives of anti-HIV agents carbovir and abacavir, were efficiently synthesized from a common intermediate . Their antitumor and antiviral activities were evaluated and the results indicate norabacavir showed comparable anti-HIV activity to that of abacavir.     

First total synthesis of (+/-)-stemonamide and (+/-)-isostemonamide

[structure: see text] The total synthesis of the tetracyclic alkaloids stemonamide (1) and isostemonamide (2) is presented. The key step is the reaction between a silyloxyfuran and an N-acyliminium ion. The second quaternary center is created by an intramolecular aldol spirocyclization. After 1,4-addition of an appropriate side chain, the methyl and double bond are installed by Mannich reaction. The seven-membered ring is closed by intramolecular nucleophilic displacement.