Controlling Anomeric Selectivity, Reactivity, and Regioselectivity in Glycosylations Using Protecting Groups

Boltje, Thomas J.; Liu, Lin; Boons, Geert‐Jan

doi:10.1002/9781119006435.ch4

Cited by 6 publications

(3 citation statements)

References 112 publications

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“…The glycosylation of oleanolic acid at C-3 was performed with the microfluidic system (Table ), as well as with the batch system for comparison (see Table S2). Glycosylation using acetylated 2a did not give the protected diglycoside 7a ; instead, the acyloxonium ion intermediate derived from the acetyl imidate donor produced orthoester 8a , which then rearranged to acetylated oleanolic acid 9 . The structure of orthoester 8a was determined by a chemical shift in the 1 H NMR at the anomeric proton compared to the β glycosidic bond.…”

Section: Resultsmentioning

confidence: 99%

“…Micromixing of 5 , 6a , and a catalytic amount of TMSOTf at different temperatures provided diglycoside 7a in only ∼20% yield (entries 2–5), and orthoester 8a was observed as a byproduct in ∼60% yield. Mild reaction conditions utilizing catalytic TMSOTf in lower temperature caused the preferential formation of 8a . On the other hand, a stoichiometric amount of TMSOTf promoted the C-3 glycosylation at room temperature, and diglycoside 7a was obtained in 83% yield without the formation of orthoester 8a (entry 7), whereas at 0 °C, the yield of 7a was decreased (entry 6).…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of Bisdesmosidic Oleanolic Acid Saponins via a Glycosylation-Deprotection Sequence under Continuous Microfluidic/Batch Conditions

et al. 2017

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We report the first synthesis of a series of bisdesmosidic oleanolic acid saponins using microflow reactor Comet X-01 via a continuous flow glycosylation-batch deprotection sequence. The main results of this study can be summarized as follows: (1) The microfluidic glycosylation of oleanolic acid at C-28 was achieved in quantitative yield and was applied to the synthesis of six C-28-monoglycosidic saponins. (2) The microfluidic glycosylation of oleanolic acid at C-3 was achieved in good yield without orthoester byproduct formation and was applied to the synthesis of three bisdesmosidic saponins. (3) The continuous synthesis of saponins via a microfluidic glycosylation-batch deprotection sequence was achieved in four steps involving two purifications. Thus, the continuous microfluidic glycosylation-deprotection process is expected to be suitable for the preparation of a library of bisdesmosidic oleanolic acid saponins for in vivo pharmacological studies.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis of Bisdesmosidic Oleanolic Acid Saponins via a Glycosylation-Deprotection Sequence under Continuous Microfluidic/Batch Conditions

et al. 2017

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“…Estos cambios están gobernados por diversos efectos, cinéticos, termodinámicos, elec-trónicos y relaciones con los catalizadores y condiciones de reacción. (Boltje, 2016) Es así como se pueden elaborar hipótesis teóricas para predecir la configuración obtenida. Esto puede trabajarse teóricamente con los alumnos para ampliar sus conocimientos de la fisicoquímica orgánica.…”

Section: Anómeros Cinética Termodinámica Y Catálisisunclassified

Proyecto de innovación en el laboratorio: una nueva práctica experimental en síntesis orgánica

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Esteche

Bejarano

et al. 2022

TrayectoriasUniversitarias

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La asignatura Química Orgánica II se dicta en la Facultad de Ciencias Exactas para distintas carreras. Es una materia del quinto cuatrimestre, se encuentra luego de un ciclo de formación básica de dos años. Es una de las materias básicas más importantes para estas carreras, ya que sus contenidos se centran en el estudio de las estructuras y de la reactividad de las moléculas bioorgánicas. A pesar de ser una asignatura de suma importancia, debido principalmente a sus contenidos, sus trabajos prácticos de laboratorio presentan algunas deficiencias. Estos problemas se relacionan con su organización teórica, conceptual, didáctica y también, con su puesta en práctica. En este sentido realizamos un diagnóstico de la situación y llevamos a cabo una propuesta de innovación con un formato de “Taller de Práctica Experimental en Síntesis Orgánica”. Este taller se propone como la unidad de reemplazo, en el programa de la asignatura, de las actuales prácticas de laboratorio. Se busca generar una propuesta superadora mediante la incorporación de un espacio de práctica de excelencia, trabajo individual y reflexión; pretendiendo aportar a la formación profesional en consistencia con el perfil de egresado propio de las carreras que incluyen a la asignatura.

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Regioselective Dechloroacetylations Mediated by Ammonium Acetate: Practical Syntheses of 2,3,4,6‐Tetra‐O‐chloroacetyl‐glycopyranoses and Cinnamoyl Glucose Esters

et al. 2020

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Abstract2,3,4,6‐Tetra‐O‐chloroacetyl‐glycopyranoses are key precursors for the formation of glycosyl donors which are important building blocks in carbohydrate chemistry. Inexpensive ammonium acetate (NH4OAc) was found to be an effective reagent for anomeric dechloroacetylations in carbohydrates, giving 2,3,4,6‐tetra‐O‐chloroacetyl‐glycopyranoses in excellent yields. This strategy is convenient for operation and purification, and thus suitable for the large‐scale synthesis. Based on this methodology, two cinnamoyl glucose esters were successfully prepared.

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Controlling Anomeric Selectivity, Reactivity, and Regioselectivity in Glycosylations Using Protecting Groups

Cited by 6 publications

References 112 publications

Synthesis of Bisdesmosidic Oleanolic Acid Saponins via a Glycosylation-Deprotection Sequence under Continuous Microfluidic/Batch Conditions

Synthesis of Bisdesmosidic Oleanolic Acid Saponins via a Glycosylation-Deprotection Sequence under Continuous Microfluidic/Batch Conditions

Proyecto de innovación en el laboratorio: una nueva práctica experimental en síntesis orgánica

Regioselective Dechloroacetylations Mediated by Ammonium Acetate: Practical Syntheses of 2,3,4,6‐Tetra‐O‐chloroacetyl‐glycopyranoses and Cinnamoyl Glucose Esters

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