Manipulation of free carbohydrates via stannylene acetals. Preparation of β-per-O-acyl derivatives of d-mannose, l-rhamnose, 6-O-trityl-d-talose, and d-lyxose

Hodosi, György; Kòváč, Pavol

doi:10.1016/s0008-6215(97)00155-9

Cited by 17 publications

(7 citation statements)

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“…Regioselectivity is a prominent challenge in organic chemistry in general, and in carbohydrate chemistry in particular, since carbohydrates contain several hydroxyl groups of similar reactivity. However, small differences in reactivity can nonetheless be utilized so that a desired protection pattern can be achieved in one or few steps without making use of complex reaction sequences. , For example, organotin reagents, such as tributyltin oxide or dibutyltin oxide, , are often used to accomplish regioselective protection, including acylation, − alkylation, − silylation, , sulfonylation, ,, and glycosylation. − The tin intermediates are easily prepared, and the methods are reliable and high-yielding, having become widely employed. However, the origin of the resulting regioselectivities has not been fully clarified.…”

Section: Introductionmentioning

confidence: 99%

Stereoelectronic Control in Regioselective Carbohydrate Protection

et al. 2012

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Organotin-mediated regioselective protection has been extensively used in organic synthesis for many years. However, the mechanistic origin of the resulting regioselectivity is still not clear. By the comparison of the steric and stereoelectronic effects controlling the geometry of five-membered rings formed from neighboring group participation, from intramolecular acyl group migration, or from orthoester transesterification on pyranoside rings, a theory on the pattern resulting from the reaction with dibutyltin oxide is presented. It is thus suggested that the regioselectivity of organotin-mediated protection is controlled by analogous steric and stereoelectronic effects as in neighboring group participation and acyl group migration, mainly dependent on the stereoelectronic effects of the pyranoside itself, and not related to complex stannylene structures. An organotin protection mechanism is also suggested, emanating from steric and stereoelectronic effects, nucleophilicity, and organotin acyl migration.

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Section: Introductionmentioning

confidence: 99%

Stereoelectronic Control in Regioselective Carbohydrate Protection

et al. 2012

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“…27,28 Treatment of glycosides with e.g. dibutyltin oxide gives stannylene Using this strategy, regioselective acylation, 29,30 alkylation, 31,32 silylation, 33 sulfonylation 30,34,35 and glycosylation 36,37 is possible.…”

Section: Tin Mediated Protection Of Glycosidesmentioning

confidence: 99%

Regioselective modification of unprotected glycosides

Jäger

Minnaard

2016

Chem. Commun.

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Selective modification of unprotected carbohydrates is difficult due to the similar reactivity of the hydroxyl groups. In carbohydrate synthesis, therefore, even straightforward transformations often require multiple synthetic steps. The development of selective methods for carbohydrate modification is consequently highly desired. This review describes the methods for the regio- and chemoselective carbohydrate modification, with a focus on novel approaches that mainly apply transition metal catalysis and organocatalysis, and discusses the challenges and opportunities in this field.

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“…Using this method, peracetylated β--mannose has been synthesised from -mannose in excellent yield. 78 Moreover 233 has been elaborated to the tetrasaccharide 236 in good yield. 79 It is possible to couple two sugar moieties through both anomeric centres using stannylene chemistry as shown by Nicolaou et al 17 β-selectivity is seen in reaction with a secondary sugar acceptor, plus the method seems limited to armed/reactive donors (Scheme 43 and Table 10).…”

Section: Dibutylstannylene Complexesmentioning

confidence: 99%