A convergent synthetic route to a tetrasaccharide related to PI-88, which allows the incorporation of a fluorescent BODIPY-label at the reducing-end, has been developed. The strategy, which features the use of 1,2-methyl orthoesters (MeOEs) as glycosyl donors, illustrates the usefulness of suitably-designed BODIPY dyes as glycosyl labels in synthetic strategies towards fluorescently-tagged oligosaccharides. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Novel, linker-free, BODIPY-carbohydrate derivatives containing sugar residues at positions C2 and C6 are efficiently obtained by, hitherto unreported, Ferrier-typeC-glycosylation of 8-aryl-1,3,5,7-tetramethyl BODIPYs with commercially available tri-O-acetyl-glucal followed by saponification. This transformation, which involves the electrophilic aromatic substitution (SEAr) of the dipyrrin framework with an allylic oxocarbenium ion, provides easy access to BODIPY-carbohydrate hybrids with excellent photophysical properties and a weaker tendency to aggregate in concentrated water solutions. © 2021 The Authors. Published by American Chemical Society

The combination of carbohydrates with BODIPY fluorophores gives rise to a family of BODIPY-carbohydrate hybrids or glyco-BODIPYs, which mutually benefit from the encounter. Thus, from the carbohydrates standpoint, glyco-BODIPYs can be regarded as fluorescent glycoconjugate derivatives with application in imaging techniques, whereas from the fluorophore view the BODIPY-carbohydrate hybrids benefit from the biocompatibility, water-solubility, and reduced toxicity, among others, brought about by the sugar moiety. In this Account we have intended to present the collection of available methods for the synthesis of BODIPY-carbohydrate hybrids, with a focus on the chemical transformations on the BODIPY core. © 2021 The Authors. Published by The Chemical Society of Japan & Wiley-VCH GmbH

Hitherto unreported 2,6-dipropargyl-1,3,5,7-tetramethyl BODIPYs can be efficiently prepared by a Nicholas reaction/decomplexation protocol from 1,3,5,7-tetramethyl BODIPYs. The title compounds, which improve the BODIPY photostability by retaining their inherent photophysical and photochemical properties, can be engaged in efficient copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click-typereactions with azido derivatives to provide all-BODIPY-triads or conjugated BODIPYs. © 2021 The Authors. Published by American Chemical Society.

A series of fluorescent boron-dipyrromethene (BODIPY, 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) dyes have been designed to participate, as aglycons, in synthetic oligosaccharide protocols. As such, they served a dual purpose: first, by being incorporated at the beginning of the process (at the reducing-end of the growing saccharide moiety), they can function as fluorescent glycosyl tags, facilitating the detection and purification of the desired glycosidic intermediates, and secondly, the presence of these chromophores on the ensuing compounds grants access to fluorescently labeled saccharides. In this context, a sought-after feature of the fluorescent dyes has been their chemical robustness. Accordingly, some BODIPY derivatives described in this work can withstand the reaction conditions commonly employed in the chemical synthesis of saccharides; namely, glycosylation and protecting-group manipulations. Regarding their photophysical properties, the BODIPY-labeled saccharides obtained in this work display remarkable fluorescence efficiency in water, reaching quantum yield values up to 82 \%, as well as notable lasing efficiencies and photostabilities. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

The development of efficient and stable red and near-IR emitting materials under hard radiation doses and/or prolonged times is a sought-after task due to their widespread applications in optoelectronics and biophotonics. To this aim, novel symmetric all-BODIPY-triads, -pentads, and -hexads have been designed and synthesized as light-harvesting arrays. These photonic materials are spectrally active in the 655–730 nm region and display high molar absorption across UV–visible region. Furthermore, they provide, to the best of our knowledge, the highest lasing efficiency (up to 68 \%) and the highest photostability (tolerance >1300 GJ mol−1) in the near-IR spectral region ever recorded under drastic pumping conditions. Additionally, the modular synthetic strategy to access the cassettes allows the systematic study of their photonic behavior related to structural factors. Collectively, the outstanding behavior of these multichromophoric photonic materials provides the keystone for engineering multifunctional systems to expedite the next generation of effective red optical materials. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

A concise synthetic route from methylmalonate to a tetravalent aliphatic scaffold has been developed. The ensuing tetra-tethered derivative is equipped with two hydroxyl groups, as well as orthogonal alkene and alkyne functionalities. The usefulness of the scaffold has been demonstrated with the preparation of two representative multivalent derivatives: (i) a tetravalent compound containing two D-mannose units, one fluorescent boron-dipyrromethene (BODIPY) dye and a suitably functionalized amino acid and (ii) by way of dimerization and saponification, a water-soluble tetramannan derivative containing two fluorescent BODIPY units. Additionally, photophysical measurements conducted on these derivatives support the viability of the herein designed single and double BODIPY-labeled carbohydrate-based clusters as fluorescent markers. © 2019 by the authors.

Fluorescent difluoroboron dipyrromethenes (BODIPYs), have been accessed in a one-pot synthetic operation from phthalides and pyrroles, a process that involves O-ethylation of phthalides with Meerwein's reagent (Et 3 OBF 4 ) and reaction of the ensuing tetrafluoroborate salts with pyrrole, followed by treatment with BF 3 · OEt 2 . These derivatives are endowed with a ortho-hydroxymethyl 8-C-aryl group for further derivatization and/or conjugation to, among others, carbohydrates. The new conjugate derivatives benefit from the optimal characteristics of BODIPYs as fluorescent dyes, including in some instances water-solubility (in the case of conjugation to unprotected carbohydrates). The different kinds of BODIPY-carbohydrate derivatives are compounds of potential interest for biological studies. ©2019 IUPAC & De Gruyter. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. For more information, please visit: http://creativecommons.org/licenses/by-nc-nd/4.0/ 2019.

Novel pyranose derivatives that display Ferrier- and Ferrier-Nicholas-like reactivity have been designed. These systems: 1-C-alkynyl-2-deoxy-2-C-methylene pyranosides (Ferrier), and their corresponding dicobalthexacarbonyl alkenyl derivatives (Ferrier-Nicholas), which can be accessed by a concise synthetic route from commercially available tri-O-acetyl-d-glucal, allow the incorporation of two nucleophiles (at positions C-3 and C-2′) in the pyranose ring. The study of these systems has resulted in the discovery of novel reaction patterns that allow, among others, access to open-chain derivatives, branched pyranosides, 1,6-anhydro derivatives and, when reacting with indole, access to a new family of tetracyclic indole-containing carbohydrate derivatives, namely, cyclohepta[b]indole-fused glycals. The latter are, most likely, formed by a bis Ferrier-type rearrangement followed by an unusual intramolecular 7-endo-dig Friedel–Crafts alkenylation of one of the indole moieties by the C-1 alkyne. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Hexacarbonyldicobalt–C-3-alkynyl-substituted glycal derivatives, when treated with BF3·OEt2 give rise to Nicholas-stabilized Ferrier cation intermediates (Ferrier–Nicholas cations) that react with alcohols or C-nucleophiles to give C-3-branched 2,3-unsaturated glycosides or C-glycosides, respectively. α-C-Glycosides were the sole compounds obtained when allyltrimethylsilane was used as the nucleophile. On the contrary, the reaction of C-3-alkynylglycals with heteroaryl or alcohol nucleophiles led to anomeric mixtures in which the β-anomers prevailed. The presence of the hexacarbonyldicobalt–C-3-alkynyl substituent seems to be of key importance in the stereoselectivity of these transformations, since the reaction of C-3-alkynylglycals – devoid of the hexacarbonyldicobalt moiety – showed a preferred α-stereoselectivity. Furthermore, a bis(indolyl) linear compound was obtained from the reaction of a hexacarbonyldicobalt–C-3-alkynylglycal with 2 equiv. of indole. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

The transformation of glycals (1,2-unsaturated cyclic carbohydrate derivatives) into 2,3-unsaturated glycosyl derivatives, currently termed Ferrier rearrangement, is a well-established synthetic procedure with ample use in the fields of carbohydrate and organic chemistry. This article highlights the developments in the Ferrier rearrangement published in the literature since the last review, in 2013, to early 2016. © 2017 The Royal Society of Chemistry.

Herein we describe the synthesis, and computationally aided photophysical characterization of a new set of urea-bridged bis-BODIPY derivatives. These new dyads are efficiently obtained by a one-pot tandem Staudinger/aza-Wittig ureation protocol, from easily accessible meso-phenyl ortho-azidomethyl BODIPYs. These symmetric bis-BODIPYs outstand by a high absorption probability and excellent fluorescence and laser emission in less polar media. Nevertheless, this emission ability decreases in more polar media, which is ascribed to a light-induced charge-transfer from the urea spacer to the dipyrrin core, a process that can be modulated by appropriate changes in the substitution pattern of the BODIPY core. Furthermore, this ureation protocol can also be employed for the direct conjugation of our BODIPY-azides to amine-containing compounds, thus providing access to fluorescent non-symmetric ureas. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

The presence of an unsaturation in a pyranose derivative provides a powerful handle for the creation of new compounds displaying a variety of molecular skeletons. This contribution focuses on investigations related to the use of pyranose glycals in the creation of skeletally-diverse derivatives that have appeared in the literature during the last eight years. © The Royal Society of Chemistry 2016.

Glycosylation of alcohol derivatives with D-mannose and D-glucose derived methyl 1,2-orthobenzoates can be promoted by commercially available acid-washed 300 molecular sieves (AW-MS), which functions both as promoter and as a drying agent in an operationally simple process. In this manner, glycosides can be obtained in good to excellent yields at room temperature, reflux, or under microwave (MW) heating. The usefulness of the process has been shown with the preparation of some diterpene glycosides. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Unsaturated carbohydrate derivatives are useful intermediates in synthetic transformations leading to a variety of compounds. The aim of this review is to highlight the rich chemistry of Δ-2,3 unsaturated pyranosides, emphasizing the variety of transformations that have been carried out in these substrates during the last decade. © 2015 by the authors; licensee MDPI.

Novel substrates that combine dicobalt hexacarbonyl propargyl (Nicholas) and pyranose-derived allylic (Ferrier) cations have been generated by treatment of hexacarbonyldicobalt (C-1)-alkynyl glycals with BF3 .Et2O. The study of these cations has resulted in the discovery of novel reaction pathways that have shown to be associated to the nature of O-6 substituent in the starting alkynyl glycals. Accordingly, compounds resulting from ring expansion (oxepanes), ring contraction (tetrahydrofurans), or branched pyranoses, by incorporation of nucleophiles, can be obtained from 6-O-benzyl, 6-hydroxy, or 6-O-silyl derivatives, respectively. The use of a 6-O-allyl alkynyl glycal led to a suitable funtionalized oxepane able to experience an intramolecular Pauson-Khand cyclization leading to a single tricyclic derivative. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbapyranoses, i.e., pyranose derivatives whose ring oxygen has been replaced by a methylene group, are currently recognized as valuable carbohydrate mimetics. A plethora of methods are available for their preparation, and among them the radical cyclization of suitably functionalized carbohydrate derivatives has already positioned itself as a reliable synthetic method. The present review aims to give an overview of the different synthetic strategies based on radical cyclization that have been employed in their preparation. Recent contributions from our research group are included, which will serve to delineate the scope and limitations of these methods. © 2014 Bentham Science Publishers.

Carbohydrates have been recognized as privileged structures for the regio- and stereo-controlled appendage of pharmacophores to generate new derivatives with potential application in drug discovery processes. Even though most of the carbohydrate templates have been generated from pyranoses, other sugar derivatives have also been employed in the assembly of such structures. In this review, attention has been directed to the use of sugar-furanose platforms, and an account of the recent developments in the generation of furanose-based templates aiming at the generation of molecular diversity, including those from our research group, is presented. © 2014 Bentham Science Publishers.

Pyranosidic allylic (Ferrier) cations that share dicobalt hexacarbonyl propargyl (Nicholas) stabilization at C-1, can be easily generated by treatment of hexacarbonyldicobalt alkynyl glycals with BF3·OEt2, and display a remarkable reactivity leading to a variety of products. The substituent at O-6 in these glycals plays a pivotal role in directing the outcome of the transformations. Accordingly, 6-O-benzyl or 6-O-allyl groups cause a series of transformations resulting in the stereoselective formation of oxepanes through a process that involves an initial hydride transfer step from the allyl or benzyl substituent to the Ferrier-Nicholas cation. On the contrary, 6-OH derivatives undergo an overall ring contraction to branched tetrahydrofuran derivatives. 6-O-Silyl derivatives, in the presence of heteroaryl nucleophiles, were transformed into C-3 branched bis-C-Cglycosides, containing two of such molecules. © 2014 IUPAC & De Gruyter.

Two complementary one-pot, three component synthetic strategies based on copper(I)-catalyzed azide - alkyne cycloadditions (CuAAC) have been developed, which allow the efficient assembly of glycosyl-derived alkynes or azides with highly fluorescent boron-dipyrromethene (BODIPY) cores containing azido or alkyne moieties, respectively. The resulting carbohydrate - BODIPY derivatives display excellent photophysical and laser properties that relate to the spacer (amino group or aromatic ring) employed in each of the synthetic protocols. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA.