Pradip Shit and All debenzylidenated products were characterized by NMR spectral analysis. <>/Subtype/Link/Rect[335.45 249 350.53 258]>> Arin Gucchait, The efficacy of this methodology is comparable to the conventional hydrogenation involving hydrogen gas and Pd/C, whereas it does not require handling of a flammable gas. Removal of benzylidene acetal and benzyl ether by using a combination of triethylsilane and 10% Pd/C. Published 14 Jan 2013. endobj Copyright © 2006 Elsevier Ltd. All rights reserved. Please enable Javascript and Cookies to allow this site to work correctly! Hamad H. Al Mamari, 2013, 9, 74–78. Functionalization of carbohydrate intermediates is essential for their assembly towards the synthesis of complex oligosaccharides [1-9]. This work was supported by CSIR, New Delhi [Project No. E.; Backinowsky, L. V. https://doi.org/10.1016/j.tetlet.2006.03.189. The license is subject to the Beilstein Journal of Organic Chemistry terms and conditions: (http://www.beilstein-journals.org/bjoc). A. Almohseni, 16 0 obj 2013, 9, 74–78. <>/Subtype/Link/Rect[134.32 463.5 205.59 470.5]>> Keywords: benzylidene; glycoside; Pd/C; transfer hydrogenation; triethylsilane. The noteworthy features of the reaction condition are: (a) neutral conditions; (b) compatibility with a large number of functional groups used in the protection of carbohydrates (e.g., acetyl, benzoyl, phthaloyl, 2-(trimethylsilyl)ethyl, 4-methoxyphenyl, etc. 26, No. bAfter short-column chromatography; cPreparation reported earlier. <>/Subtype/Link/Rect[276.17 80 291.41 89]>> Call for papers is open for this thematic issue. %PDF-1.4 Scheme 1: Benzyl ethers and benzylidene acetal in a compound can be removed in one pot by using these reaction conditions (Table 1, entries 3, 4, 9, 10, 12). A number of methods have been reported for the removal of benzylidene acetals by using strong protic and Lewis acids [10,11,15] as well as some heteroge-neous acidic catalysts [16,17]. %���� ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Anup Kumar Misra, Herman O. Sintim, David M. Hodgson, © 2013 Santra et al; licensee Beilstein-Institut. endobj Interestingly, monoreduction of 1,2-benzylidene acetal occurred very cleanly without deprotection of the benzyl group when carrying out the experiment at 0 … Register and get informed about new articles. The effect of triethylsilane and 10% Pd/C on the removal of benzylidene acetal is presented in Table 1. The benzylidene acetal can also be regioselectively opened under reductive conditions to produce partially benzyl-ated derivatives [12-14]. Another method of deprotection was carried out by hydrogenation of F benzylidene acetal groups with 10% Pd–C. 17 0 obj We use cookies to help provide and enhance our service and tailor content and ads. A Convenient Method for Highly Selective Deprotection of Benzylidene Acetals from Sugars. Known compounds gave acceptable NMR spectra that matched the previously reported data. In this context, the development of a mild, neutral reaction condition for the removal of benzylidene acetals would be useful in the derivatization of a carbohydrate framework. To a solution of compound 1 (500 mg, 1.36 mmol) and 10% Pd(OH)2/C (50 mg) in CH3OH (5 mL) was added Et3SiH (650 μL, 4.07 mmol) portionwise, and the reaction mixture was stirred at room temperature for an appropriate time, given in Table 1. <>/Subtype/Link/Rect[143.55 106 170.56 115]>> 27 0 obj https://doi.org/10.3762/bjoc.9.9 <>/Subtype/Link/Rect[476.34 532 527 540]>> <>/Subtype/Link/Rect[108.08 223 127.43 232]>> Copyright © 2020 Elsevier B.V. or its licensors or contributors. Double bonds, hydroxyl groups, acetate groups, and highly acid-sensitive groups such as furyl, tert -butyl ethers, and ketoximes are tolerated. endobj (1996). Younes Fegheh-Hassanpour and The reaction conditions were equally effective for the removal of 4-methoxybenzylidene acetal (Table 1, entries 13–15). 21 0 obj The benzylidene acetal can also be regioselectively opened under reductive conditions to produce partially benzylated derivatives [12-14]. x��Xɒ�F��+�2-��k��Vkk�m�R����`�,@QX��>���_N @šQ(� ��|����e}����0��؁�}s-�B��K Beilstein J. Org. <>/Subtype/Link/Rect[151.09 80 166.32 89]>> However, most of the above-mentioned methodologies have several shortcomings, such as harsh conditions, formation of unwanted byproducts, longer reaction time, incompatibility of functional groups, use of expensive reagents, fire hazard, etc. E.; Backinowsky, L. V. Hasegawa, A.; Ogawa, M.; Ishida, H.; Kiso, M. Nicolaou, K. C.; Veale, C. A.; Hwang, C.-K.; Hutchinson, J.; Prasad, C. V. C.; Ogilvie, W. W. Codée, J. D. C.; Ali, A.; Overkleeft, H. S.; van der Marel, G. A. Kumar, P. S.; Kumar, G. D. K.; Baskaran, S. Nicolaou, K. C.; Veale, C. A.; Hwang, C.-K.; Hutchinson, J.; Prasad, C. V. C.; Ogilvie, W. W. Adinolfi, M.; De Napoli, L.; Di Fabio, G.; Iadonisi, A.; Montesarchio, D.; Piccialli, G. Hasegawa, A.; Ogawa, M.; Ishida, H.; Kiso, M. Kochetkov, N. K.; Byramova, N. E.; Tsvetkov, Yu. Conversions of carbohydrate derivatives effected with Et3SiH and 10% Pd/C. 22 0 obj 23 0 obj This is an Open Access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A variety of carbohydrate diol derivatives were prepared from their benzylidene derivatives in excellent yield. 28 0 obj Submit your original research! <>/Subtype/Link/Rect[137.56 197 165.16 206]>> This method was successfully applied to the synthesis of the C1–C14 fragment of dolabelides. <>/Subtype/Link/Rect[125.65 145 154.62 154]>> <>/Subtype/Link/Rect[297.5 503.5 360.51 510.5]>> endobj (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) View Show abstract eAzide group reduced to amine. 20 0 obj Selective hydrogenolysis of benzyl ethers in the presence of benzylidene acetals with Raney nickel. How to cite this article: In summary, the efficient deprotection of carbohydrate derivatives containing benzylidene acetal and O-benzyl groups under catalytic transfer hydrogenation conditions has been developed by using a combination of triethylsilane and 10% Pd/C. Allyl ether was reduced and benzyl ethers were removed under the reaction conditions, as expected from the earlier report [22] (Table 1, entry 8 and entries 3, 4, 9, 10, 12). The combined filtrate was concentrated under reduced pressure to give the crude product, which was passed through a short pad of SiO2 with EtOAc as eluant to give pure compound 2 (330 mg, 87%). endobj Clean deprotection of carbohydrate derivatives containing benzylidene acetals and benzyl ethers was achieved under catalytic transfer hydrogenation conditions by using a combination of triethylsilane and 10% Pd/C in CH3OH at room temperature. A simple method to remove selectively a benzyl group protecting a hydroxyl function in the presence of a benzylidene acetal by catalytic hydrogenolysis with Raney nickel is reported. Selective hydrogenolysis of benzyl ethers in the presence of benzylidene acetals and PMB ethers with Raney nickel in ethanol has been effected in complex substrates. endobj 19 0 obj reported the removal of benzyl esters/ethers and the reduction of alkenes/alkynes by catalytic transfer hydrogenation using a combination [22] of triethylsilane (Et3SiH) and 10% Pd/C. Chem. In addition, benzylidene acetal is selectively cleaved in the presence of isopropylidene ketal. ); (c) clean and high yielding; (d) no unwanted byproduct formation; (e) can be carried out at room temperature; (f) no flammable gas is required. Subscribe to our Latest Articles RSS Feed. endobj Subscribe to our Latest Articles RSS-Feed. In this study 4,6-O-benzylidene acetals were used as model compounds for deciphering the mechanism of regioselective openings using a variety of reducing agents.Competitive isotopic studies aiming at primary and secondary isotope effects, as well as an electron-deficient … aAbbreviations used: PMP: 4-methoxyphenyl; Phth: phthaloyl. In summary, the efficient deprotection of carbohydrate derivatives containing benzylidene acetal and O-benzyl groups under catalytic transfer hydrogenation conditions has been developed by using a combination of triethylsilane and 10% Pd/C.The efficacy of this methodology is comparable to the conventional hydrogenation involving hydrogen gas and Pd/C, whereas it does not require handling of … It can be removed under acidic hydrolysis as well as under neutral conditions (e.g., hydrogenolysis). Register for the Beilstein Open Science Symposium 2020 - it's free and online! Chem. Adinolfi, M.; De Napoli, L.; Di Fabio, G.; Iadonisi, A.; Montesarchio, D.; Piccialli, G. Codée, J. D. C.; Ali, A.; Overkleeft, H. S.; van der Marel, G. A. Kumar, P. S.; Kumar, G. D. K.; Baskaran, S. Kochetkov, N. K.; Byramova, N. E.; Tsvetkov, Yu. Being operationally simple and high yielding, these reaction conditions will certainly be accepted as a useful alternative to those currently existing in this area. Anup Kumar Misra, Abhijit Sau and endobj 29 0 obj endobj endobj Mandal et al. dSpectra recorded after per-O-acetylation using acetic anhydride and pyridine (1:1; v/v). We report herein our findings on the removal of benzylidene acetal using a combination of triethylsilane and 10% Pd/C (Scheme 1). endobj Hasanain A. <>/Subtype/Link/Rect[149.61 119 188.94 128]>> Despite the importance of regioselective reductive openings of cyclic acetals, mechanistic details are scarce. <>stream 881-886. By continuing you agree to the use of cookies. 25 0 obj benzylidene; glycoside; Pd/C; transfer hydrogenation; triethylsilane, Synthesis of the tetrasaccharide repeating unit of the, Convergent synthesis of the tetrasaccharide repeating unit of the cell wall lipopolysaccharide of, Alkylation of lithiated dimethyl tartrate acetonide with unactivated alkyl halides and application to an asymmetric synthesis of the 2,8-dioxabicyclo[3.2.1]octane core of squalestatins/zaragozic acids.

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