Investigations Directed Toward the Synthesis of New Cyclopentanoids Using Optically Active Bicyclo[2.2.1]heptene Monoester

The synthetic utilization of a chiral building block obtained by the enzymatic asymmetric hydrolysis of a symmetric diester having the bicyclo[2.2.1]heptene system was investigated. Several cyclopentanoids have been synthesized in high yields in enatiomerically enriched forms with the use of simple reactions. These compounds are expected to serve as useful chiral synthons for cyclopentane-containing natural products and pharmaceuticals

Non-Enzymatic Desymmetrization Reactions in Aqueous Media

Symmetric organic compounds are generally obtained inexpensively, and therefore they can be attractive building blocks for the total synthesis of various pharmaceuticals and natural products. The drawback is that discriminating the identical functional groups in the symmetric compounds is difficult. Water is the most environmentally benign and inexpensive solvent. However, successful organic reactions in water are rather limited due to the hydrophobicity of organic compounds in general. Therefore, desymmetrization reactions in aqueous media are expected to offer versatile strategies for the synthesis of a variety of significant organic compounds. This review focuses on the recent progress of desymmetrization reactions of symmetric organic compounds in aqueous media without utilizing enzymes

A Pyrene Maleimide with a Flexible Linker for Sampling of Longer Inter-Thiol Distances by Excimer Formation

Pyrene-containing compounds are commonly used in a number of fluorescence-based applications because they can form excited-state dimers (excimers) by stacking interaction between excited-state and ground-state monomers. Their usefulness arises from the facts that excimer formation requires close proximity between the pyrenes and that the excimer emission spectrum is very different from that of the monomers. One of many applications is to assess proximity between specific sites of macromolecules labeled with pyrenes. This has been done using pyrene maleimide, a reagent that reacts with reduced thiols of cysteines, but its use for structural studies of proteins has been rather limited. This is because the introduction of two cysteines at sufficiently close distance from each other to obtain excimer fluorescence upon labeling with pyrene maleimide requires detailed knowledge of the protein structure or extensive site-directed mutagenesis trials. We synthesized and tested a new compound with a 4-carbon methylene linker placed between the maleimide and the pyrene (pyrene-4-maleimide), with the aim of increasing the sampling distance for excimer formation and making the use of excimer fluorescence simpler and more widespread. We tested the new compound on thiol-modified oligonucleotides and showed that it can detect proximity between thiols beyond the reach of pyrene maleimide. Based on its spectroscopic and chemical properties, we suggest that pyrene-4-maleimide is an excellent probe to assess proximities between cysteines in proteins and thiols in other macromolecules, as well as to follow conformational changes

Re cent Desymmetrization Reactions By CALB

Enzyme reactions are among the most environmentally friendly and important asymmetric reactions for organic synthesis. Candida Antarctica lipase B (CALB) is one of the most extensively utilized enzymes for various asymmetric reactions. It catalyzes a variety of asymmetric reactions, such as hydrolysis, esterification, and amidation. However, as the studies of desymmetrization reactions of symmetric compounds catalyzed by CALB is rather limited, this commentary focuses on some recent examples of desymmetrization reactions mediated by CALB

Among The Smallest Building Blocks in Organic Synthesis: Oxalate Half-Esters and Their Derivatives

Although oxalate half-esters and their derivatives are among the smallest units of building blocks in organic synthesis, they are very important for synthesis of a wide range of significant compounds. Utilized as building blocks for pharmaceuticals and natural products, they are typically prepared by partial hydrolysis of symmetric diesters or by partial alkylation of oxalyl chloride. Their structural properties that enable them to undergo radical deoxygenation are also applied to various significant reactions, further leading to synthesis of complex pharmaceuticals and natural products. Oxalate half-esters are also applied to the preparation of new polymers with novel properties

RECENT ADVANCEMENTS IN THE SYNTHESIS OF HALF-ESTERS AND THEIR APPLICATIONS

Half-esters are important building blocks for the synthesis of pharmaceuticals, polymers and natural products. Therefore, synthetic methodologies for both chiral and racemic half-esters have been actively investigated for decades. This short review summarizes recent progress in the synthesis of half-esters and their applications including the studies from our laboratories