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A method for the synthesis of natural lignan lactones was developed by utilizing chiral dirhodium(II) carboxamidate catalysts. The synthetic process is characterized by C-H insertion which was initiated by the overlap of the carbon p-orbital and sigma-orbital of the metal carbene and the reacting C-H bond. The formation of beta-substituted-gamma-butyrolactones was initiated by the reaction of chiral Rh2(MPPIM)4 catalysts to fully aliphatic systems.

A method for the synthesis of natural lignan lactones was developed by utilizing chiral dirhodium(II) carboxamidate catalysts. The synthetic process is characterized by C-H insertion which was initiated by the overlap of the carbon p-orbital and sigma-orbital of the metal carbene and the reacting C-H bond. The formation of beta-substituted-gamma-butyrolactones was initiated by the reaction of chiral Rh2(MPPIM)4 catalysts to fully aliphatic systems.

The five dirhodium(II) tetracarboxamidates derived from chiral methyl 1-acyl-2-oxoimidazolidine-4(S)-carboxylates each has unique capabilities as a chiral catalyst for highly stereoselective metal carbene transformations. Monoclinic crystals in space group P2(sub 1) are formed by the simplest member of the series, (2,2-cis)-dirhodium(II) tetrakis(methyl 1-acyl-2-oxoimidazolidine-4(S)-carboxylate), (2,2-cis)-Rh2(4S-MACIM)4. Four of them have been prepared by ligand substitution with dirhodium(II) acetate.

The feasibility of using chiral dirhodium(II) tetrakis(methyl 2-pyrrolidone-5 S-carboxylate), Rh2(5S-MEPY)4 and its enantiomer, Rh2(5R-MEPY)4, as catalysts for the intramolecular cyclopropanations of allylic and homoallylic diazoacetates and diazoacetamides was evaluated. Results showed that the use of the chiral dirhodium(II) catalysts produced cyclopropanes with excellent enantioselectivity.

A highly enantio‐ and regioselective hydrosulfonylation of 1,3‐dienes with sulfonyl hydrazides has been realized by using a palladium catalyst containing a monodentate chiral spiro phosphoramidite ligand. The reaction provided an efficient approach to synthetically useful chiral allylic sulfones. Mechanistic studies suggest that the reaction proceeds through the formation of an allyl hydrazine intermediate and subsequent rearrangement to the chiral allylic sulfone product. The transformation of the allyl hydrazine intermediate to the product is the enantioselectivity‐determining step. [ABSTRACT FROM AUTHOR]

An enantioselective total synthesis of pentacyclic proaporphine alkaloid (−)‐misramine has been achieved. The synthetic route features a Pictet‐Spengler cyclization to construct the fused B and C rings and a sequence of Baeyer‐Villiger oxidation, Pinnick oxidation, and pinacol‐type cyclization to install the α‐hydroxy ketal moiety. The absolute configuration of the pentacyclic framework was elucidated by X‐ray single‐crystal analyses of (−)‐11‐demethoxymisramine. [ABSTRACT FROM AUTHOR]

A carbene insertion into electron‐deficient C−H bonds of 1,3‐diesters, β‐ketoesters, β‐ketonitriles, and malononitriles was realized by using CuCN/PCy3 as the catalyst. The reaction provides a straightforward approach to the synthetically important multi‐substituted succinic acid derivatives. A plausible reaction mechanism with cyclopropanation/ring opening as key steps was proposed based on control experiments. [ABSTRACT FROM AUTHOR]

This study was designed to determine whether plasma CXCL12 levels in postmenopausal osteoporosis (PMOP) patients are related to disease severity. A total of 91 PMOP females were recruited, and 88 postmenopausal non-osteoporotic (PMNOP) women and 90 healthy females were incorporated as controls. Dual-energy X-ray absorptiometry was utilised to explore bone-mineral density (BMD). The Genant semi-quantitative grading scale was used for vertebral fractures, and plasma CXCL12/SDF-1 levels were investigated by ELISA. Plasma TNF-α and C-telopeptide cross-linked collagen type 1 (CTX-1) were also tested. The Oswestry Disability Index (ODI) and a visual analogue scale (VAS) were completed in order to assess clinical severity. Plasma CXCL12 levels were considerably elevated in PMOP females compared to PMNOP women and healthy controls. Plasma CXCL12 concentrations were positively correlated with the Genant grading system. We observed significant and negative correlations of plasma CXCL12 levels with lumbar spine, femoral neck and total hip BMD. Moreover, plasma CXCL12 concentrations were positively correlated to VAS and ODI, as well as plasma TNF-α and CTX-1 levels. In conclusion, elevated plasma CXCL12 levels are correlated with disease severity in PMOP females. [ABSTRACT FROM AUTHOR]