Synlett

The synthesis of volicitin involved the condensation of l-(+)-glutamine with 17(S)-hydroxylinolenoic acid, derived from a Wittig reaction between the C10–C18 phosphonium salt and the C1–C9 aldehyde. The phosphonium salt was prepared through the alkynylation of a (Z)-allylic phosphate with an alkyne derived from (2S)-but-3-yn-2-ol. The deuterated aldehyde was derived with a 96% deuteration ratio by reduction of the C1–C9 methyl ester with NaBD4, followed by oxidation. Subsequently, 9-D
1-volicitin was synthesized from the monodeuterated aldehyde by using the Wittig reaction and condensation with l-(+)-glutamine.

A nickel-catalyzed aminomethylation of aryl or heteroaryl iodides or bromides for the preparation of protected primary benzylamines is reported. This cross-electrophile reductive protocol engages carbamate-protected, glycine-derived N-hydroxyphthalimide (NHP) esters in an efficient decarboxylative cross-coupling in only two hours. The catalyst and NHP ester reagents are commercially available or can be synthesized in one step on a decagram scale with no chromatography.

A new method for the intramolecular electrophilic ipso-cyclization of alkynes with triflic anhydride-activated sulfoxides, followed by demethylation with triethylamine in one pot, is described for the synthesis of 3-thiospiro[4.5]-decatrienones in moderate to good yields. This method provides a facile strategy for assembling the sulfur-substituted spirocyclic compounds.

α-Aminoboronic acids and their derivatives are important synthetic targets. Our research interest has been focused on the synthesis and applications of MIDA (N-methyliminodiacetic acid) protected aminoboronates. Herein we report syntheses of regioisomeric β-borylated azidoalcohols. The geminal azidoboronate represents a rare example of an α-azidoalcohol and is produced through trapping of oxonium ions that develop during the rearrangement of α-boryl aldehydes. The vicinal azidoboronate can be obtained from α-bromoacetyl MIDA boronate and enables the preparation of aziridine MIDA boronate through the Staudinger reaction.

The reliance on wasteful stoichiometric reagents to accomplish dehydration reactions such as esterification, amidation, and alcohol substitution is a longstanding challenge in synthetic chemistry. To address this problem, an electrochemical approach has been developed as a new conceptual platform for dehydration reactions. As a proof-of-concept demonstration, an electrochemical esterification protocol has been described that proceeds at room temperature, without acid or base additives, and without consuming stoichiometric reagents. This approach therefore overcomes key complications of esterification chemistry, and we envision that it will similarly enable improvements to a range of important, related transformations.1 Introduction2 An Electrochemical Design for Catalytic Dehydration3 Electrochemical Esterification4 Conclusions

Carbohydrates are synthetically challenging molecules with vital biological roles in all living systems. To better understand the biological functions of this fundamentally important class of molecules, novel methodologies are needed, including site-selective functionalization and glycosylation reactions. This account describes our efforts toward the development of novel methodologies for site-selective functionalization of carbohydrates and stereoselective glycosylation through various acylation reactions.

Synlett 2024; 35: V-DOI: 10.1055/s-0043-1763662Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents

Polycations are an important class of water-soluble polymers because they form polyion complexes with DNA. Thus, the synthesis of polycations with controlled monomer sequences will be of increasing importance for the formation of well-defined polyion complexes. In this study, cationic homopolymer and alternating copolymer with the dense triazole backbone were synthesized by copper(I)-catalyzed azide–alkyne cycloaddition polymerization. The polycations obtained were characterized by potentiometric and turbidimetric titrations, and by complex formation with poly(acrylic acid).

A stereoselective synthesis of the C1–C13 segment of poecillastrin C has been achieved. The C1–C4 moiety was derived from diallyl l-tartrate, and the amide group at the C3 position was constructed by means of a traceless Staudinger reaction. The C1–C13 segment was submitted to model studies, including esterification with a bulky alcohol at the C1 position and Stille coupling with vinyl iodide at the C13 position. The reactivity of the C1 position was affected by the neighboring C2-protective group. When the C2 hydroxy group was protected as a TBS ether, the C1 carboxylic acid did not undergo esterification with a bulky secondary alcohol, whereas the p-methoxybenzylidene N,O-acetal afforded a 2,4-dimethyl-3-pentyl ester. Stille coupling of the C1–C13 segment with 1-iodohept-1-ene gave the southern part of the poecillastrin C macrolactam attached to simplified eastern and western parts.

We present a novel method for the chemoselective House–Meinwald rearrangement of trisubstituted epoxides under mild conditions with the use of simple perfluorinated disulfonimides as Brønsted acid catalysts. We isolated the α-quaternary aldehyde products in yields of 27–97% using catalyst loadings as low as 0.5 mol% on a scale of 1 mmol. In addition, we show the stereospecific rearrangement using an enantioenriched substrate, which makes this method suitable for applications in total synthesis of natural products.