Pentaerythritol: A Versatile Substrate in Organic Transformations, Centralization on the Reaction Medium

BACKGROUND

Pentaerythritol (2,2-bis (hydroxymethyl) propane-1,3-diol) as white crystalline odorless solid has been synthesized in 1891. Pentaerythritol is multifaceted species in many compounds, which are wildly utilized in medicine and industry. Also, multicomponent reactions (MCRs) play a crucial role in organic and medicinal chemistry. Hence, in these reactions, pentaerythritol is a versatile substrate for the synthesis of many polyfunctionalized products, because of the presence of the neopentane core and one hydroxyl group in each of the four terminal carbons.

OBJECTIVE

The review describes pentaerythritol multicomponent reactions in the presence of different solvents in the reaction medium to produce various compounds including pentaerythritols. This review covers the literature relevant up to 2018.

CONCLUSION

It is obvious from the provided review that a great deal of research has been done in this field, utilizing various mediums (solvent-free conditions, aqueous media, and organic solvents) for the synthesis of the products of containing pentaerythritols. This classification is based on the importance of economic and environmental friendly reactions. Due to the whole aforesaid reports, some reactions required heat for their progress, and some others were accompanied by microwave or ultrasonic waves.

Selective chemistry of tripentaerythritol — Synthesis of acetals and their derivatives

Tripentaerythritol was converted efficiently into 2′,2′′:6′,6′′:10′,10′′-tri-O-cyclohexylidene-2,2,6,6,10,10-hexakis(hydroxymethyl)-4,8-dioxa-1,11-undecandiol (4) by the toluenesulfonic acid catalysed reaction with cyclohexanone in a mixture of N,N-dimethylformamide and benzene. Reaction of tripentaerythritol with benzaldehyde under similar conditions gave an easily separated mixture of the four possible stereoisomers. Structures of these stereoisomers were assigned based on 1H and 13C NMR chemical shifts using trends previously observed for the dibenzylidene acetals of dipentaerythritol, whose structures had been established unambiguously by X-ray crystallography. It was found that reduction of the mixture of benzylidene acetals to 2,6,10-tris(benzyloxymethyl)-4,8-dioxa-1,11-undecanediol could be accomplished using triethylsilane with ethylaluminium dichloride as the Lewis acid after a number of commonly used conditions for this transformation failed.Key words: pentaerythritol, tripentaerythritol, dipentaerythritol, acetals, benzylidene acetals, reduction.

Pentaerythrityltetramine Scaffolds for Solid-Phase Combinatorial Chemistry1

Straightforward synthesis for two pentaerythrityltetramine precursors, 2,2-bis(azidomethyl)propane-1,3-diamine (1) and 2-[N-(allyloxycarbonyl)aminomethyl]-2-azidomethylpropane-1,3-diamine (2), has been described. Both propane-1,3-diamines have been attached by reductive amination to a solid-supported backbone amide linker derived from 4-(4-formyl-3,5-dimethoxyphenoxy)butyric acid. The presence of the two methoxy substituents on the linker is essential to avoid cross-linking between two linkers. The remaining free primary amino group of the propane-1,3-diamine moiety may then be selectively acylated with an appropriately protected amino acid using conventional N,N-dicyclohexylcarbodiimide/1-hydroxybenzotriazole (DCC/HOBt) activation without any interference by the secondary amino function. The latter group may be subsequently acylated by an anhydride method. Sequential reduction of the azido group and removal of the allyloxycarbonyl protection from 2 allow further coupling of two different amino acids, and hence, this handle may be utilized in construction of branched structures containing four different amino acids or peptides. Solid-supported 1 may, in turn, be used for the synthesis of similar constructs containing two identical branches. It is worth noting that no acid-labile protecting groups are required in this approach, and hence, this dimension may be saved for the cleavage of the linker. The applicability of the scaffolds to library synthesis has been demonstrated by preparation of 11 pentaerythrityl-branched tetra- and octapeptides.

New potential dendritic cores: Selective chemistry of dipentaerythritol

Methods were developed to convert dipentaerythritol efficiently into di-O-benzylidene, di-O-cyclohexylidene, di-O-1-ethylpropylidene, and di-O-methylene diacetals. The known di-O-benzylidene acetal, considered to be a single isomer, was shown to be close to a statistical mixture of the cis,cis-, cis,trans-, and trans,trans-isomers. Structures were established by a combination of NMR spectroscopy and X-ray crystallography. Reaction of the di-O-benzylidene acetals with benzyl chloride and potassium hydroxide surprisingly gave good to excellent yields of the monobenzyl ethers. An explanation for this observation was advanced. The dibenzyl derivatives of the di-O-benzylidene acetals were formed by reaction of their dianions with benzyl bromide in DMF. Selective reduction of the di-O-benzylidene acetals with triethylsilane and boron trifluoride etherate gave 2',6'-di-O-benzyldipentaerythritol. A crown ether was formed in modest yield (12%) by reaction of the dianion of the di-O-methylene acetal with α,α'-dibromo-m-xylene in DMF. Key words: dipentaerythritol, pentaerythritol, acetals, dendrimer, selective benzylation, crown ether.

A pentaerythritol-based molecular scaffold for solid-phase combinatorial chemistry

A convergent synthesis has been developed for the preparation of solid-phase bound construct 1, consisting of an orthogonally protected trifunctional core structure that is attached to TentaGel via a photocleavable linker. [structure: see text]

The anomalous reactivity of the bis(dibutylstannylene) acetal of pentaerythritol: a case of triple activation

The only dibutyltin derivative of pentaerythritol which is observed by refluxing with dibutyltin oxide in methanol is a bis(dibutylstannylene) acetal. This is converted to the expected dibenzyl ether with benzyl bromide, in the presence of tetraethylammonium bromide in boiling toluene, but benzoylation at room temperature gives a tribenzoate. A mechanism is suggested to account for this triple activation.