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Here, we report the synthesis and characterization of organo-soluble chiral thiol-monolayer-protected gold nanorods. The resulting gold nanorods respectively covered with two opposite enantiomers via the strong covalent Au-S linkage were found to not only be stable in both organic media and solid state, but also show optical activity. Their circular dichroism (CD) spectra exhibited a mirror image relationship, indicating that enantiomeric thiol surfactant on gold surface can produce the corresponding enantiomeric gold nanorods. The densely packed azobenzene thiolmonolayer on gold surface exhibited a photoresponsive behavior upon irradiation with 254 nm light instead of 365nm light, which was found to have an effect on plasmonic absorption of gold nanorods., Published in Langmuir, v27 n1 p98-103, 2011. Prepared in cooperation with the Liquid Crystal Institute, Kent State University, Kent, OH, and the Department of Chemical Engineering, Case Western Reserve University, Cleveland, OH.

Marine-derived microorganisms produce structurally diverse butenolides possessing a variety of bioactivities. Described here is the total synthesis of (4S, 10R)-4-hydroxy-10-nnethyl-11-oxododec-2-en-1,4-olide and a related butenolide containing anti stereochemistry at C10-C11. A three-module coupling strategy has been established for synthesis of the stereoisomers of the naturally Occurring butenolides by assembling the C3-C7 and C9-C12 fragments via double alkylation of a 1,3-dithiane. The C10-C11 stereochemistry could be easily controlled by an asymmetric aldol condensation, while the butenolide unit was efficiently constructed according to the ring-closing metathesis protocol. (C) 2008 Elsevier Ltd. All rights reserved.

Aromatic amide-derived phosphanes (Aphos) are hemilabile P,O-coordinating ligands, which, when combined with a Pd precursor, yield a promising precatalyst system for Suzuki-Miyaura cross-coupling reactions. A focused library of Aphos ligands has been constructed for structural optimization, with the target of improving catalytic efficacy. By using microwave irradiation at accurately regulated temperature, an expeditious and reproducible one-pot synthesis and screening protocol was designed and experimentally validated. The success is based on a unique self-assisted molecular editing (SAME) process in which both the substrate and the product molecules catalyze formation of the product. Thus, starting from a 4-chlorobenzamide-derived Aphos as the substrate, parallel reactions with a selected set of arylboronic acids, in the absence of an added external phosphane ligand to Pd, produced a family of structurally edited Aphos ligands. The resultant reaction mixture containing the new Aphos, the Pd species, and the base could be used for in situ screening of the Aphos efficacy in a reference Suzuki-Miyaura coupling reaction. The structures of all Aphos ligands were characterized by P-31 NMR spectroscopy and their catalytic profiles in the reference reaction were evaluated by HPLC analysis. These data allowed the identification of an efficient Aphos ligand, capable of promoting room-temperature Suzuki-Miyaura coupling of unactivated and sterically hindered aryl chlorides with arylboronic acids under mildly basic conditions.

Aromatic amide-derived phosphanes (Aphos) are hemilabile P,O-coordinating ligands, which, when combined with a Pd precursor, yield a promising precatalyst system for Suzuki-Miyaura cross-coupling reactions. A focused library of Aphos ligands has been constructed for structural optimization, with the target of improving catalytic efficacy. By using microwave irradiation at accurately regulated temperature, an expeditious and reproducible one-pot synthesis and screening protocol was designed and experimentally validated. The success is based on a unique self-assisted molecular editing (SAME) process in which both the substrate and the product molecules catalyze formation of the product. Thus, starting from a 4-chlorobenzamide-derived Aphos as the substrate, parallel reactions with a selected set of arylboronic acids, in the absence of an added external phosphane ligand to Pd, produced a family of structurally edited Aphos ligands. The resultant reaction mixture containing the new Aphos, the Pd species, and the base could be used for in situ screening of the Aphos efficacy in a reference Suzuki-Miyaura coupling reaction. The structures of all Aphos ligands were characterized by P-31 NMR spectroscopy and their catalytic profiles in the reference reaction were evaluated by HPLC analysis. These data allowed the identification of an efficient Aphos ligand, capable of promoting room-temperature Suzuki-Miyaura coupling of unactivated and sterically hindered aryl chlorides with arylboronic acids under mildly basic conditions.

Marine-derived microorganisms produce structurally diverse butenolides possessing a variety of bioactivities. Described here is the total synthesis of (4S, 10R)-4-hydroxy-10-nnethyl-11-oxododec-2-en-1,4-olide and a related butenolide containing anti stereochemistry at C10-C11. A three-module coupling strategy has been established for synthesis of the stereoisomers of the naturally Occurring butenolides by assembling the C3-C7 and C9-C12 fragments via double alkylation of a 1,3-dithiane. The C10-C11 stereochemistry could be easily controlled by an asymmetric aldol condensation, while the butenolide unit was efficiently constructed according to the ring-closing metathesis protocol. (C) 2008 Elsevier Ltd. All rights reserved.

Aromatic amide-derived phosphanes (Aphos) are hemilabile P,O-coordinating ligands, which, when combined with a Pd precursor, yield a promising precatalyst system for Suzuki-Miyaura cross-coupling reactions. A focused library of Aphos ligands has been constructed for structural optimization, with the target of improving catalytic efficacy. By using microwave irradiation at accurately regulated temperature, an expeditious and reproducible one-pot synthesis and screening protocol was designed and experimentally validated. The success is based on a unique self-assisted molecular editing (SAME) process in which both the substrate and the product molecules catalyze formation of the product. Thus, starting from a 4-chlorobenzamide-derived Aphos as the substrate, parallel reactions with a selected set of arylboronic acids, in the absence of an added external phosphane ligand to Pd, produced a family of structurally edited Aphos ligands. The resultant reaction mixture containing the new Aphos, the Pd species, and the base could be used for in situ screening of the Aphos efficacy in a reference Suzuki-Miyaura coupling reaction. The structures of all Aphos ligands were characterized by P-31 NMR spectroscopy and their catalytic profiles in the reference reaction were evaluated by HPLC analysis. These data allowed the identification of an efficient Aphos ligand, capable of promoting room-temperature Suzuki-Miyaura coupling of unactivated and sterically hindered aryl chlorides with arylboronic acids under mildly basic conditions.

Marine-derived microorganisms produce structurally diverse butenolides possessing a variety of bioactivities. Described here is the total synthesis of (4S, 10R)-4-hydroxy-10-nnethyl-11-oxododec-2-en-1,4-olide and a related butenolide containing anti stereochemistry at C10-C11. A three-module coupling strategy has been established for synthesis of the stereoisomers of the naturally Occurring butenolides by assembling the C3-C7 and C9-C12 fragments via double alkylation of a 1,3-dithiane. The C10-C11 stereochemistry could be easily controlled by an asymmetric aldol condensation, while the butenolide unit was efficiently constructed according to the ring-closing metathesis protocol. (C) 2008 Elsevier Ltd. All rights reserved.

Amphidinolide Y, a 17-membered cytotoxic macrolide isolated from marine dinoflagellates, has been synthesized via ring-closing metathesis to assemble the congested trisubstituted (E)-double bond. The seco precursor was prepared from readily available chiral synthons with the tetrahydrofuran ring formed via 5-endo epoxide ring-opening cyclization. It was found that the C6-keto seco substrate showed higher reactivity toward Grubbs' second generation catalyst while Schrock's Mo catalyst was completely inactive for formation of the macrocycle.

Amphidinolide Y, a 17-membered cytotoxic macrolide isolated from marine dinoflagellates, has been synthesized via ring-closing metathesis to assemble the congested trisubstituted (E)-double bond. The seco precursor was prepared from readily available chiral synthons with the tetrahydrofuran ring formed via 5-endo epoxide ring-opening cyclization. It was found that the C6-keto seco substrate showed higher reactivity toward Grubbs' second generation catalyst while Schrock's Mo catalyst was completely inactive for formation of the macrocycle.

Amphidinolide Y, a 17-membered cytotoxic macrolide isolated from marine dinoflagellates, has been synthesized via ring-closing metathesis to assemble the congested trisubstituted (E)-double bond. The seco precursor was prepared from readily available chiral synthons with the tetrahydrofuran ring formed via 5-endo epoxide ring-opening cyclization. It was found that the C6-keto seco substrate showed higher reactivity toward Grubbs' second generation catalyst while Schrock's Mo catalyst was completely inactive for formation of the macrocycle.