Stereoselective Synthesis of 1,1′‐Disaccharides by Organoboron Catalysis

Izumi, Sanae; Kobayashi, Yusuke; Takemoto, Yoshiji

doi:10.1002/ange.202004476

“…Such substrates uniquely contain a non-static hemiacetal moiety that enables dynamic equilibration between the α-and β-anomers, thus elevating the stereoselectivity challenge. Delightfully, by applying catalyst 27 and N,N-diisopropylethylamine (DIPEA) as a base 68,69 , we were able to functionalize 15s-u cleanly with concomitant enantio-, diastereo-, siteand anomeric selectivity to yield 1,2-cis 17s-u. Hence, this unravelled a deeper level of catalytic intricacy: a dynamic kinetic resolution-type control by the organoboron catalyst can also be activated by our strategy to control anomeric selectivity.…”

Section: Articlementioning

confidence: 99%

A synergistic Rh(I)/organoboron-catalysed site-selective carbohydrate functionalization that involves multiple stereocontrol

Rao

¹

,

Caiming

²

,

Demarque

³

et al. 2022

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Site-selective functionalization is a core synthetic strategy that has broad implications in organic synthesis. Particularly, exploiting chiral catalysis to control site selectivity in complex carbohydrate functionalizations has emerged as a leading method to unravel unprecedented routes into biologically relevant glycosides. However, robust catalytic systems available to overcome multiple facets of stereoselectivity challenges to this end still remain scarce. Here we report a synergistic chiral Rh(I)- and organoboron-catalysed protocol, which enables access into synthetically challenging but biologically relevant arylnaphthalene glycosides. Our method depicts the employment of chiral Rh(I) catalysis in site-selective carbohydrate functionalization and showcases the utility of boronic acid as a compatible co-catalyst. Crucial to the success of our method is the judicious choice of a suitable organoboron catalyst. We also determine that exquisite multiple aspects of stereocontrol, including enantio-, diastereo-, regio- and anomeric control and dynamic kinetic resolution, are concomitantly operative.

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“…The excellent stereoselectivity achieved in present method is attributed to the stability of 9 a – 9 c in acidic glycosylation conditions. Recently, an alternative 1,1′‐glycosylation method was also reported by Takemoto et al [38] …”

Section: Resultsmentioning

confidence: 97%

Tunable Strategy for the Asymmetric Synthesis of Sulfoglycolipids from Mycobacterium tuberculosis To Elucidate the Structure and Immunomodulatory Property Relationships

Mondal

¹

,

Tseng

²

,

Tan

³

et al. 2022

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We developed a versatile asymmetric strategy to synthesize different classes of sulfoglycolipids (SGLs) from Mycobacterium tuberculosis. The strategy features the use of asymmetrically protected trehaloses, which were acquired from the glycosylation of TMS α‐glucosyl acceptors with benzylidene‐protected thioglucosyl donors. The positions of the protecting groups at the donors and acceptors can be fine‐tuned to obtain different protecting‐group patterns, which is crucial for regioselective acylation and sulfation. In addition, a chemoenzymatic strategy was established to prepare the polymethylated fatty acid building blocks. The strategy employs inexpensive lipase as a desymmetrization agent in the preparation of the starting substrate and readily available chiral oxazolidinone as a chirality‐controlling agent in the construction of the polymethylated fatty acids. A subsequent investigation on the immunomodulatory properties of each class of SGLs showed how the structures of SGLs impact the host innate immunity response.

show abstract

Tunable Strategy for the Asymmetric Synthesis of Sulfoglycolipids from Mycobacterium tuberculosis To Elucidate the Structure and Immunomodulatory Property Relationships

Mondal

¹

,

Tseng

²

,

Tan

³

et al. 2022

Angewandte Chemie

0

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We developed a versatile asymmetric strategy to synthesize different classes of sulfoglycolipids (SGLs) from Mycobacterium tuberculosis. The strategy features the use of asymmetrically protected trehaloses, which were acquired from the glycosylation of TMS α‐glucosyl acceptors with benzylidene‐protected thioglucosyl donors. The positions of the protecting groups at the donors and acceptors can be fine‐tuned to obtain different protecting‐group patterns, which is crucial for regioselective acylation and sulfation. In addition, a chemoenzymatic strategy was established to prepare the polymethylated fatty acid building blocks. The strategy employs inexpensive lipase as a desymmetrization agent in the preparation of the starting substrate and readily available chiral oxazolidinone as a chirality‐controlling agent in the construction of the polymethylated fatty acids. A subsequent investigation on the immunomodulatory properties of each class of SGLs showed how the structures of SGLs impact the host innate immunity response.

show abstract

Stereoselective Synthesis of 1,1′‐Disaccharides by Organoboron Catalysis

Cited by 5 publications

References 86 publications

A synergistic Rh(I)/organoboron-catalysed site-selective carbohydrate functionalization that involves multiple stereocontrol

A synergistic Rh(I)/organoboron-catalysed site-selective carbohydrate functionalization that involves multiple stereocontrol

Tunable Strategy for the Asymmetric Synthesis of Sulfoglycolipids from Mycobacterium tuberculosis To Elucidate the Structure and Immunomodulatory Property Relationships

Tunable Strategy for the Asymmetric Synthesis of Sulfoglycolipids from Mycobacterium tuberculosis To Elucidate the Structure and Immunomodulatory Property Relationships

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