614752-07-7

Upstream product

• 100-39-0 benzyl bromide 
• 181480-80-8 6-O-tert-butyldimethylsilanyl-1-O-methyl-α-D-galactopyranoside 
• 18162-48-6 tert-butyldimethylsilyl chloride 
• 40010-11-5 methyl α-D-galactopyranoside 3-benzyl ether 

Downstream Products

• 614752-11-3 methyl 3-O-benzyl-6-O-(tert-butyldimethylsilyl)-2,4-bis-O-(methylsulfanylthiocarbonyl)-α-D-galactopyranoside 
• 614752-28-2 (2S,4S,6S)-4-(benzyloxy)-2-[(tert-butyldimethylsiloxy)methyl]-6-methoxytetrahydro-2H-pyran 
• 614752-14-6 methyl 3-O-benzyl-2,4,6-trideoxy-α-D-threo-hept-6-ynopyranoside 
• 114976-68-0 (2S,4S,6S)-4-Benzyloxy-6-methoxy-tetrahydro-pyran-2-carbaldehyde 
• 87391-88-6 [(2S,4S,6S)-4-(benzyloxy)-6-methoxytetrahydro-pyran-2-yl]-methanol 

Relevant academic research and scientific papers

Enantioselective Desymmetrization of 2-Aryl-1,3-propanediols by Direct O-Alkylation with a Rationally Designed Chiral Hemiboronic Acid Catalyst That Mitigates Substrate Conformational Poisoning

Enantioselective desymmetrization by direct monofunctionalization of prochiral diols is a powerful strategy to prepare valuable synthetic intermediates in high optical purity. Boron acids can activate diols toward nucleophilic additions; however, the design of stable chiral catalysts remains a challenge and highlights the need to identify new chemotypes for this purpose. Herein, the discovery and optimization of a bench-stable chiral 9-hydroxy-9,10-boroxarophenanthrene catalyst is described and applied in the highly enantioselective desymmetrization of 2-aryl-1,3-diols using benzylic electrophiles under operationally simple, ambient conditions. Nucleophilic activation and discrimination of the enantiotopic hydroxy groups on the diol substrate occurs via a defined chairlike six-membered anionic complex with the hemiboronic heterocycle. The optimal binaphthyl-based catalyst 1g features a large aryloxytrityl group to effectively shield one of the two prochiral hydroxy groups on the diol complex, whereas a strategically placed "methyl blocker"on the boroxarophenanthrene unit mitigates the deleterious effect of a competing conformation of the complexed diol that compromised the overall efficiency of the desymmetrization process. This methodology affords monoalkylated products in enantiomeric ratios equal or over 95:5 for a wide range of 1,3-propanediols with various 2-aryl/heteroaryl groups.

Regio/site-selective alkylation of substrates containing a: Cis -, 1,2- or 1,3-diol with ferric chloride and dipivaloylmethane as the catalytic system

In this study, we reported the regio/site-selective alkylation of substrates containing a cis-, 1,2- or 1,3-diol with FeCl3 as a key catalyst. A catalytic system consisting of FeCl3 (0.01-0.1 equiv.) and dipivaloylmethane (FeCl3/dipivaloylmethane = 1/2) was used to catalyze the alkylation in the presence of a base. The produced selectivities and isolated yields were similar to those obtained by methods using the same amount of FeL3 (L = acylacetone ligand) as the catalyst in most cases. The previously reported FeL3 catalysts for alkylation are not commercially available and have to be synthesized prior to use. In contrast, FeCl3 and dipivaloylmethane (Hdipm) are very common and inexpensive nontoxic reagents in the lab, thereby making the method much greener and easier to handle. Mechanism studies confirmed for the first time that FeCl3 initially reacts with two equivalents of Hdipm to form [Fe(dipm)3] in the presence of a base in acetonitrile, followed by the formation of a five or six-membered ring intermediate between [Fe(dipm)3] and two hydroxyl groups of the substrate. A subsequent reaction between the cyclic intermediate and the alkylating agent results in selective alkylation of the substrate.

Highly Efficient Selective Benzylation of Carbohydrates Catalyzed by Iron(III) with Silver Oxide and Bromide Anion as Co-catalysts

A highly efficient, green, and regioselective method for the benzylation of diols and polyols was developed. With the use of Ag2O (0.6 equiv.) and tetrabutylammonium bromide (0.1 equiv.) as co-catalysts, the iron(III)-catalyzed benzylation reaction proceeded to completion at 40 °C within 2–3 h and gave the products in high yields with high regioselectivities. A mechanism involving the principle of enhanced basicity of Ag2O by soft anions was proposed.

Regioselective alkylation of carbohydrates and diols: A cheaper iron catalyst, new applications and mechanism

As an extension of our previous research on the regioselective protection of carbohydrates and diols, we developed an iron catalyst, Fe(dibm)3 (dibm = diisobutyrylmethane), which has an unusually broad catalytic scope in the selective monoalkyl

An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols

In this study, [Fe(dibm)3] (dibm=diisobutyrylmethane) is shown to have unusually broad scope as a catalyst for the selective monoalkylation of a diverse set of 1,2- and 1,3-diol-containing structures. The mechanism is proposed to proceed via a cyclic dioxolane-type intermediate, formed between the iron(III) species and two adjacent hydroxyl groups. This approach represents the first transition-metal catalysts that are able to replace stoichiometric amounts of organotin reagents in regioselective alkylation. The reactions generally lead to very high regioselectivities and high yields, on par with, or better than, previous methods used for regioselective alkylation.

Regioselective benzylation of diols and polyols by catalytic amounts of an organotin reagent

An efficient one-pot method for the selective benzylation of diols and polyols using 0.1 equiv. of organotin reagents and tetrabutylammonium bromide as catalyst has been developed. The diols and polyols containing a cis-vicinal diol were regioselectively

Regioselective alkylation of carbohydrate derivatives catalyzed by a diarylborinic acid derivative

Regioselective, catalyst-controlled monoalkylations of cis-vicinal diol motifs in carbohydrate derivatives, using a diphenylborinic ester precatalyst, are described. Selective installation of benzyl, naphthylmethyl, 4-bromobenzyl and benzyloxymethyl protective groups at a single secondary hydroxy group of ten representative carbohydrate derivatives illustrates the scope of this method. This new mode of catalytic reactivity represents an operationally simple method to access useful monoalkylated building blocks while avoiding the use of stoichiometric quantities of organotin reagents.

Substituent effects on the SmI2/Pd(0)-promoted carbohydrate ring-contraction of 5-alkynylpyranosides

The effect of substituents on the reactivity and stereoselectivity of the SmI2/Pd(0)-promoted ring-contraction of 5-alkynylpyranosides has been examined using substrates substituted only at selected positions. While formation of 2-ethynylcyclopentanols takes place efficiently, an internal alkyne did not afford the expected product. The presence of peripheral alkoxy substituents leads to variable stereoselectivities that depend on the number and orientation of such groups. Thus, an isolated OBn substituent at C(3) (carbohydrate numbering) exerts a significant stereochemical control while additional substitution with the same group at C(4) either enhances or drastically reduces stereoselectivity depending on its orientation (α or β, respectively).