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An efficient stereoselective synthesis of furanoverrillin (<b>5</b>), a highly functionalized core of verrillin (<b>1</b>), is reported. The synthetic strategy is based on constructing bicyclic lactone <b>17</b> prior to the 10-membered ring macrocyclization. The effect of the C₄ methyl group on the furan reactivity is also discussed

Synthesis of a Highly Functionalized Core of Verrillin

An efficient stereoselective synthesis of furanoverrillin (<b>5</b>), a highly functionalized core of verrillin (<b>1</b>), is reported. The synthetic strategy is based on constructing bicyclic lactone <b>17</b> prior to the 10-membered ring macrocyclization. The effect of the C₄ methyl group on the furan reactivity is also discussed

Enantioselective Total Synthesis of Reveromycin B

Enantioselective Total Synthesis of Reveromycin

Enantioselective Total Synthesis of Reveromycin B

Enantioselective Total Synthesis of Reveromycin

Synthetic Studies on Norrisolide: Enantioselective Synthesis of the Norrisane Side Chain

Norrisolide (1) belongs to a family of marine diterpenes that are characterized by the assembly of a bicyclic core with a unique and highly oxygenated side chain (norrisane side chain). As a prelude to the synthesis of 1, we present herein a short, efficient, and enantioselective synthesis of the norrisane side chain 4. The synthetic route toward 4 departs from d-mannose and is short (11 steps), efficient, and enantioselective

Enantioselective Formal Synthesis of (−)-Englerin A via a Rh-Catalyzed [4 + 3] Cycloaddition Reaction

An enantioselective formal synthesis of (−)-englerin A (1) is reported. Key to the strategy is a Rh-catalyzed [4 + 3] cycloaddition reaction between furan 10 and diazo ester 11 that, following an intramolecular aldol condensation, produces the tricyclic scaffold of englerin. This strategy also provides a rapid, efficient, and stereoselective access to the biologically significant core motif of the guaiane sesquiterpenes

Chemical Analysis of Norrisolide-Induced Golgi Vesiculation

The chemical origin of the norrisolide-induced irreversible Golgi vesiculation was studied using a variety of norrisolide probes. This natural product was found to bind to a receptor on the Golgi membranes using the perhydroindane core fragment as the recognition element. The acetylated γ-lactol-γ-lactone side chain of norrisolide is essential for the irreversible Golgi vesiculation and can be replaced by other electrophilic motifs without loss of biological function. In particular, compound 10 reproduces the cellular phenotype of the natural product

Enantioselective Synthesis of the ABC Ring Motif of Norzoanthamine Based on Asymmetric Robinson Annulation Reactions

An enantioselective strategy for the synthesis of tetracyclic motif 5, representing the northern fragment of norzoanthamine, is presented. Key to the strategy is the use of two asymmetric Robinson annulation reactions that produce the tricyclic ABC ring system with excellent stereoselectivity. Further functionalization at the periphery of the C ring produces compound 5 containing six contiguous stereocenters of the natural product

Synthesis of 2‘-<i>O</i>-Methoxyethylguanosine Using a Novel Silicon-Based Protecting Group

A short and efficient synthesis of 2‘-O-methoxyethylguanosine (8) is described. Central to this strategy is the development of a novel silicon-based protecting group (MDPSCl2, 2) used to protect the 3‘,5‘-hydroxyl groups of the ribose. Silylation of guanosine with 2 proceeded with excellent regioselectivity and in 79% yield. Alkylation of the 2‘-hydroxyl group of 6 proceeded with methoxyethyl bromide and NaHMDS and afforded compound 7 in 85% yield, without any noticeable cleavage of the silyl protecting group and without the need to protect the guanine base moiety. Finally, deprotection of 7 was achieved using TBAF and produced 8 in 97% yield

A Ratiometric Fluorescent Viscosity Sensor

The development of a dual probe that provides ratiometric measurements of fluid viscosity is described. The design is based on coupling of a primary fluorophore with viscosity-independent fluorescence emission (blue unit) with a secondary fluorophore that exhibits viscosity-sensitive fluorescent emission quantum yield (red unit). Excitation of the secondary fluorophore can be achieved via Resonance Energy Transfer. The ratio of the fluorescence emission of these fluorophores provides an accurate, ratiometric measurement of solvent viscosity