Chemoselective Cross-metathesis Research Articles

A Diversity-Oriented Strategy for Chemical Synthesis of Glycosphingolipids: Synthesis of Glycosphingolipid LcGg4 and Its Analogues and Derivatives.

A diversity-oriented strategy was developed for the synthesis of glycosphingolipids (GSLs). This strategy was highlighted by using a simple lactoside containing the core structures of GSL glycan and lipid as the universal starting material to obtain different synthetic targets upon stepwise elongation of the glycan via chemical glycosylations and on-site remodeling of the lipid via chemoselective cross-metathesis and N-acylation. The strategy was verified with the synthesis of a lacto-ganglio GSL, LcGg4, which is a biomarker of undifferentiated malignant myeloid cells, and a series of its analogues or derivatives carrying different sugar chains and unique functionalities or molecular labels. This synthetic strategy should be widely applicable and, therefore, be utilized to rapidly access various GSLs and related derivatives by using different donors for glycosylations and different substrates for lipid remodeling following each glycosylation.

A Diversity-Oriented Strategy for Chemoenzymatic Synthesis of Glycosphingolipids and Related Derivatives.

A diversity-oriented strategy combining enzymatic glycan assembly and on-site lipid remodeling via chemoselective cross-metathesis and N-acylation was developed for glycosphingolipid (GSL) synthesis starting from a common, simple glycoside. The strategy was verified with a series of natural GSLs and GSL derivatives and showed several advantages. Most notably, it enabled two-way diversification of the glycan and lipid, including introduction of designed molecular tags, to provide functionalized GSLs useful for biological studies and applications.

Conjugation of bile esters to cellulose by olefin cross-metathesis: A strategy for accessing complex polysaccharide structures

Bile salts tend to form micelles in aqueous media and can thereby contribute to drug solubilization; they also exhibit crystallization inhibition properties that can stabilize supersaturated drug solutions. Herein, we explore conjugation of bile salts with polysaccharides to create new, amphiphilic polysaccharide derivatives with intriguing properties, portending broad utility in various applications. We introduce efficient conjugation of cholesterol (as a model steroid), lithocholic acid, and deoxycholic acid by mild, modular olefin cross-metathesis reactions. These small molecules were first modified with an acrylate group from the A-ring hydroxyl, then reacted with cellulose derivatives bearing olefin-terminated metathesis “handles”. Successful conjugation of bile acids has demonstrated chemoselective cross-metathesis with complex, polyfunctional structures, and large multi-ring systems. It also enabled an efficient, general pathway for polysaccharide-bile salt conjugates, which promise synergy for applications such as amorphous solid dispersion (ASD).

Simple Synthesis of Conjugated All-(E)-Polyenic Aldehydes, Ketones, and Esters Using Chemoselective Cross-Metathesis and an Iterative Sequence of Reactions: Application to the Synthesis of Navenone B

By using a very simple sequence of reactions such as allylation, acetylation, chemoselective cross-metathesis, and elimination, even and odd conjugated all-(E)-polyenes can be synthesized from very simple alkenes.

Combinatorial Synthesis of the 1,5-Polyol System Based on Cross Metathesis: Structure Revision of Amphidinol 3

Combinatorial synthesis of a 1,5-polyol system corresponding to the C1-C14 unit of amphidinol 3 (AM3) and its diastereomers was achieved via chemoselective cross metathesis as the key step. Comparison of (13)C NMR data of the synthetic specimens with that of AM3 led to a controversy regarding the originally proposed structure. From GC-MS analysis of the degradation product, the absolute configuration at C2 of AM3 has been revised to be R.

Efficient Syntheses of the Polyene Fragments Present in Amphidinols

The C53-C67 and C53-C65 polyene fragments of amphidinols have been synthesized in an efficient and convergent fashion from sorbic acid in good overall yields (30-31%) by employing a chemoselective cross-metathesis of a Weinreb amide and a Julia-Kocienski olefination as the key steps.

Chemoselective Cross‐Metathesis Reaction Between Electron‐Deficient 1,3‐Dienes and Olefins.

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Chemoselective cross-metathesis reaction between electron-deficient 1,3-dienes and olefins

Chemoselective cross-metathesis reactions between methyl sorbate or 1,3-dienic amides and various olefins in the presence of the Grubbs–Hoveyda catalyst have been investigated. Cross-metathesis reactions turned out to be more chemoselective with 1,3-dienic amides than with 1,3-dienic esters.

Total Synthesis of (+)-Phomopsolide C by Ring-Size Selective Ring-Closing Metathesis/Cross-Metathesis

[reaction: see text]A new strategy for the synthesis of chiral 6-substituted 5,6-dihydro-5-hydroxypyran-2-ones by ring-size selective ring-closing metathesis (RCM) and its application to a short total synthesis of (+)-phomopsolide C are described. The key bond-forming reactions in this approach are a chemoselective cross-metathesis (CM) and RCM.

Tetrafibricin: Synthesis of the C1—C13, C15—C25, and C27—C40 Fragments.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chemoselective Cross Metathesis of Bishomoallylic Alcohols: Rapid Access to Fragment A of the Cryptophycins (XIV).

AbstractFor Abstract see ChemInform Abstract in Full Text.

Tetrafibricin: synthesis of the C1-C13, C15-C25, and C27-C40 fragments.

[structure: see text] A sequence of chemoselective cross-metathesis reactions and enantioselective allyltitanations of aldehydes has been used to prepare the C1-C13, C15-C26, and C27-C40 fragments of tetrafibricin.

Chemoselective cross metathesis of bishomoallylic alcohols: rapid access to fragment a of the cryptophycins.

[reaction: see text] The racemic or enantioselective allylation of in situ formed beta,gamma-unsaturated aldehydes provides efficient access to bishomoallylic alcohols from readily available 2-vinyloxiranes. These products, when subjected to modified Grubbs cross metathesis conditions, afforded terminally homologated products in moderate to good yields with high E selectivity and without degradation of the enantiomeric excess. The compounds obtained through this two-step sequence yield fragments of an important and pharmacologically active family of cryptophycins.

Chemoselective cross-metathesis reaction. Application to the synthesis of the C1-C14 fragment of amphidinol 3.

[reaction: see text] An efficient synthesis of the C1-C14 fragment of amphidinol 3 is described. The synthesis is based on chemoselective cross-metathesis reactions and enantioselective allyltitanations.