Mild Method for 2-Naphthylmethyl Ether Protecting Group Removal Using a Combination of 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and β-Pinene

Lloyd, Dina; Bylsma, Marissa; Bright, Danielle K.; Chen, Xizhao; Bennett, Clay S.

doi:10.1021/acs.joc.7b00065

Cited by 54 publications

(48 citation statements)

References 29 publications

(111 reference statements)

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“…The Nap protecting group has emerged as a particularly valuable addition to carbohydrate chemistry [ 24 – 25 ]. Not only does it not significantly alter carbohydrate reactivity, it also can be readily cleaved under hydrogenolytic conditions as well as a variety of oxidative [ 26 ] and acid-mediated conditions [ 25 , 27 ] that are orthogonal to benzyl ethers.…”

Section: Discussionmentioning

confidence: 99%

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

Xue¹,

Han²,

Li³

et al. 2020

Beilstein J. Org. Chem.

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Lipid A, the hydrophobic domain of lipopolysaccharide (LPS), is a strong immunostimulator and therefore a valuable target for the development of novel immunomodulators. Various lipid A derivatives have been chemically synthesized in order to reduce toxicity while retaining the immunostimulatory activity. In this work, we describe a novel approach to the frequently problematic synthesis of monophosphorylated mono- and disaccharide lipid X using a combination of established chemistry and a novel 2-naphthylmethyl ether (Nap) protecting group for “permanent” protection of hydroxy groups. Of particular note is the fact that the key Nap protecting group is able to remain in the molecule until the final global deprotection step. Our synthetic strategy is not only efficient in regards to the yield of the various chemical transformations, but also robust in regards to the potential application of this route to the production of other lipid A analogs.

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Section: Discussionmentioning

confidence: 99%

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

Xue¹,

Han²,

Li³

et al. 2020

Beilstein J. Org. Chem.

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“…To overcome this problem, a variety of new reagent combinations were introduced which increase the utility of Nap Protecting group. For example, Bennett employed β‐pinene as acid scavenger, Crich used hydrogenation using Pd/C poisoned with thioether, Codée discovered HCl and HFIP, and Liu introduced HF‐pyridine as novel reagents. Borbas and co‐workers recently showed that catalytic hydrogenation can be effectively used for selective deprotection of the (2‐naphthyl)methyl (NAP) group in the presence of p ‐methoxybenzyl (PMB), benzyl and benzylidene groups in a series of monosaccharides .…”

Section: New Reagents For Old Protecting Groupsmentioning

confidence: 99%

Advances in Protecting Groups for Oligosaccharide Synthesis

Ghosh

Kulkarni

2020

Chemistry An Asian Journal

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Carbohydrates contain numerous hydroxyl groups and sometimes amine functionalities which lead to a variety of complex structures. In order to discriminate each hydroxyl group for the synthesis of complex oligosaccharides, protecting group manipulations are essential. Although the primary role of a protecting group is to temporarily mask a particular hydroxyl/amino group, it plays a greater role in tuning the reactivity of coupling partners as well as regioselectivity and stereoselectivity of glycosylations. Several protecting groups offer anchimeric assistance in glycosylation. They also alter the solubility of substrates and thereby influence the reaction outcome. Since oligosaccharides comprise branched structures, the glycosyl donors and acceptors need to be protected with orthogonal protected groups that can be selectively removed one at a time without affecting other groups. This minireview is therefore intended to provide a discussion on new protecting groups for amino and hydroxyl groups, which have been introduced over last ten years in the field of carbohydrate synthesis. These protecting groups are also useful for synthesizing non‐carbohydrate target molecules as well.

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“…4–8 Confronted with such problems in our laboratory we were intrigued by the possibility of employing 2-naphthylmethyl (Nap) ethers in place of benzyl ethers. 2-Naphthylmethyl ethers have enjoyed widespread use and continuous refinement in carbohydrate chemistry as surrogates for p -methoxybenzyl ethers since their introduction to the field by Matta, 9–14 because of their greater stability to Brønsted acids but comparable ease of removal under oxidative conditions with dichlorodicyanoquinone. However, it was the selective hydrogenolytic removal of Nap ethers in presence of benzyl ethers initially reported by Spencer 15 that suggested the possibility of their use as a possible remedy to the problem in hand.…”

Section: Introductionmentioning

confidence: 99%

Hydrogenolytic cleavage of naphthylmethyl ethers in the presence of sulfides

Adero

Jarois

Crich

2017

Carbohydrate Research

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With the aid of a series of model thioether or thioglycoside containing polyols protected with combinations of benzyl ethers and 2-naphthylmethyl ethers it is demonstrated that the latter are readily cleaved selectively under hydrogenolytic conditions in the presence of the frequently catalyst-poisoning sulfides. These results suggest the possibility of employing 2-naphthylmethyl ethers in place of benzyl ethers in synthetic schemes when hydrogenolytic deprotection is anticipated in the presence of thioether type functionality.

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Mild Method for 2-Naphthylmethyl Ether Protecting Group Removal Using a Combination of 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and β-Pinene

Cited by 54 publications

References 29 publications

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

Advances in Protecting Groups for Oligosaccharide Synthesis

Hydrogenolytic cleavage of naphthylmethyl ethers in the presence of sulfides

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