Regioselective Reductive Ring Opening of Benzylidene Acetals Using Triethylsilane and Iodine

Abstract

Novel reaction conditions have been developed for the regioselective reductive ring opening of benzylidene acetals in carbohydrate derivatives using triethylsilane and molecular iodine. The reaction is fast, compatible with most of the functional groups encountered in the oligosaccharide synthesis, and yields were excellent. The reaction conditions are equally effective in thioglycosides.

carbohydrate - benzylidene acetal - regioselective - ­iodine - triethylsilane

References and Notes

<A NAME="RD02210ST-1A">1a</A> Preparative Carbohydrate Chemistry   Hanessian S. Marcel Dekker; New York: 1997. 

<A NAME="RD02210ST-1B">1b</A> Carbohydrates in Best Synthetic Methods   Osborn HMI. Academic Press; London: 2003. 

<A NAME="RD02210ST-1C">1c</A> The Organic Chemistry of Sugars   Levy DE. Fugedi P. Taylor and Francis; New York: 2006. 

<A NAME="RD02210ST-1D">1d</A> Nicolaou KC. Mitchell HJ. Angew. Chem. Int. Ed.  2001,  40:  1576 

<A NAME="RD02210ST-2A">2a</A> Greene TW. Wuts PGM. Protective Groups in Organic Synthesis   3rd ed.:  John Wiley and Sons; New York: 1999.  p.217-224  

<A NAME="RD02210ST-2B">2b</A> Kocienski PJ. J. Chem. Soc., Perkin Trans. 1  2001,  2109 

<A NAME="RD02210ST-2C">2c</A> Meresse P. Monneret C. Bertounesque E. Tetrahedron  2004,  60:  2657 

<A NAME="RD02210ST-3">3</A> Garegg PJ. Hultberg H. Wallin S. Carbohydr. Res.  1982,  108:  97 

<A NAME="RD02210ST-4">4</A> Garegg PJ. Pure Appl. Chem.  1984,  56:  845 

<A NAME="RD02210ST-5">5</A> DeNinno MP. Etienne JB. Duplantier KC. Tetrahedron Lett.  1995,  36:  669 

<A NAME="RD02210ST-6">6</A> Debenham SD. Toone EJ. Tetrahedron: Asymmetry  2000,  11:  385 

<A NAME="RD02210ST-7">7</A> Bhattacharyya SS. Gorin PAJ. Can. J. Chem.  1969,  47:  1195 

<A NAME="RD02210ST-8">8</A> Tanaka N. Ogawa I. Yoshigase S. Nokami J. Carbohydr. Res.  2008,  343:  2675 

<A NAME="RD02210ST-9">9</A> Daragics K. Fugedi P. Tetrahedron Lett.  2009,  50:  2914 

<A NAME="RD02210ST-10">10</A> Jiang L. Chan T.-H. Tetrahedron Lett.  1998,  39:  355 

<A NAME="RD02210ST-11">11</A> Tani S. Sawadi S. Kojima M. Akai S. Sato K.-i. Tetrahedron Lett.  2007,  48:  3103 

<A NAME="RD02210ST-12A">12a</A> Wang C.-C. Luo S.-Y. Shie C.-R. Hung S.-C. Org. Lett.  2002,  4:  847 

<A NAME="RD02210ST-12B">12b</A> Shie C.-R. Tzeng Z.-H. Kulkarni SS. Uang B.-J. Hsu C.-Y. Hung S.-C. Angew. Chem. Int. Ed.  2005,  44:  1665 

<A NAME="RD02210ST-12C">12c</A> Oikawa M. Liu W.-C. Nakai Y. Koshida S. Fukase K. Kusumoto S. Synlett  1996,  1179 

<A NAME="RD02210ST-13A">13a</A> Guchhait G. Misra AK. Tetrahedron: Asymmetry  2009,  20:  1791 

<A NAME="RD02210ST-13B">13b</A> Pandey S. Ghosh S. Misra AK. Synthesis  2009,  2584 

<A NAME="RD02210ST-13C">13c</A> Panchadhayee R. Misra AK. Tetrahedron: Asymmetry  2009,  20:  1550 

<A NAME="RD02210ST-13D">13d</A> Mandal PK. Misra AK. Synthesis  2009,  1348 

<A NAME="RD02210ST-13E">13e</A> Mukherjee C. Misra AK. Tetrahedron: Asymmetry  2009,  20:  473 

<A NAME="RD02210ST-13F">13f</A> Mandal PK. Misra AK. Tetrahedron  2008,  64:  8685 

<A NAME="RD02210ST-13G">13g</A> Mandal PK. Misra AK. Glycoconjugate J.  2008,  25:  713 

<A NAME="RD02210ST-13H">13h</A> Mukherjee C. Misra AK. Tetrahedron: Asymmetry  2008,  19:  2746 

<A NAME="RD02210ST-13I">13i</A> Panchadhayee R. Misra AK. Glycoconjugate J.  2008,  25:  817 

<A NAME="RD02210ST-13J">13j</A> Kumar R. Maulik PR. Misra AK. Glycoconjugate J.  2008,  25:  511 

<A NAME="RD02210ST-13K">13k</A> Mukherjee C. Misra AK. Glycoconjugate J.  2008,  25:  611 

<A NAME="RD02210ST-13L">13l</A> Tiwari P. Misra AK. Glycoconjugate J.  2008,  25:  85 

<A NAME="RD02210ST-13M">13m</A> Mukherjee C. Misra AK. Glycoconjugate J.  2008,  25:  111 

<A NAME="RD02210ST-13N">13n</A> Mandal PK. Misra AK. Synthesis  2007,  2660 

<A NAME="RD02210ST-13O">13o</A> Agnihotri G. Mandal PK. Misra AK. Tetrahedron  2007,  63:  7240 

<A NAME="RD02210ST-14">14</A> Kartha KPR. Aloui M. Field RA. Tetrahedron Lett.  1996,  37:  5175 

<A NAME="RD02210ST-15">15</A> Sakagami M. Hamana H. Tetrahedron Lett.  2000,  41:  5547 

<A NAME="RD02210ST-16">16</A> Madiyalakan R. Chowdhary MS. Rana SS. Matta KL. Carbohydr. Res.  1986,  152:  183 

<A NAME="RD02210ST-17">17</A> You Y. Yao L. Biao Y. J. Am. Chem. Soc.  2009,  131:  12076 

<A NAME="RD02210ST-18">18</A> Soderman P. Jansson P.-E. Widmalm G. J. Chem. Soc., Perkin Trans. 2  1998,  639 

<A NAME="RD02210ST-19">19</A> Satoshi S. Kazuya T. Yoshihito U. Matsuda A. J. Org. Chem.  1998,  63:  8815 

<A NAME="RD02210ST-20">20</A> Shinya H. Seeberger PH. Chem. Asian J.  2007,  2:  1447 

<A NAME="RD02210ST-21">21</A> Yashunsky DV. Higson AP. Ross AJ. Nikolaev AV. Carbohydr. Res.  2001,  336:  243 

<A NAME="RD02210ST-22">22</A> Zhang Z. Magnusson G. J. Org. Chem.  1996,  61:  2383 

<A NAME="RD02210ST-23">23</A>

Spectroscopic data for novel products are presented below. To aid assignments, data were taken after acetylation of the products.
4-Methoxyphenyl 2,3,4-Tri- O -acetyl-6- O -benzyl-β- d -galactopyranoside (Acetylated 22)
^¹H NMR (500 MHz, CDCl₃): δ = 7.25-7.17 (m, 5 H, ArH), 6.87 (d, J = 9.0 Hz, 2 H, ArH), 6.70 (d, J = 9.0 Hz, 2 H, ArH), 5.40 (d, J = 3.3 Hz, 1 H, H-4), 5.31 (dd, J = 7.9 Hz each, 1 H, H-2), 4.99 (dd, J = 10.4, 3.4 Hz, 1 H, H-3), 4.83 (d, J = 7.9 Hz, 1 H, H-1), 4.48 (d, J = 11.9 Hz, 1 H, PhCH_2a), 4.36 (d, J = 11.9 Hz, 1 H, PhCH_2b), 3.87-3.84 (m, 1 H, H-5), 3.68 (s, 3 H, OCH₃), 3.52-3.44 (m, 2 H, H-6_a,b), 2.01, 1.99, 1.93 (3 s, 9 H, 3 COCH₃). ^¹³C NMR (125 MHz, CDCl₃): δ = 170.3, 170.1, 169.5 (3 COCH₃), 156.0-114.9 (ArC), 101.1 (C-1), 73.9, 72.9, 71.5, 69.4, 67.9, 67.8, 55.8, 21.1, 21.0, 20.9 (3 COCH₃). ESI-MS (C₂₆H₃₀O₁₀): m/z = 525.1 [M + Na]⁺.
Phenyl 2,3,4-Tri- O -acetyl-6- O -benzyl-1-seleno-β-d-glucopyranoside (Acetylated 25) ^¹H NMR (500 MHz, CDCl₃): δ = 7.59-7.21 (m, 10 H, ArH), 5.15 (t, J = 9.2 Hz, 1 H, H-3), 5.01 (t, J = 9.8 Hz, 1 H, H-2), 4.97 (t, J = 9.2 Hz, 1 H, H-4), 4.88 (d, J = 9.9 Hz, 1 H, H-1), 4.53-4.46 (2 d, J = 11.8 Hz, 2 H, PhCH₂), 3.67-3.63 (m, 1 H, H-5), 3.56-3.54 (m, 2 H, H-6_a,b), 2.14, 2.05, 1.96 (3 s, 9 H, 3 COCH₃). ^¹³C NMR (125 MHz, CDCl₃): δ = 170.4, 169.6, 169.4 (3 COCH₃), 138.2-127.6 (ArC), 81.4 (C-1), 78.9, 74.4, 73.9, 71.3, 69.4 (2 C), 21.1, 20.9 (2 C) (3 COCH₃). ESI-MS (C₂₅H₂₈O₈Se): m/z = 559.1 [M + Na]⁺.
Methyl (2,3,4-Tri- O -acetyl-6- O -benzyl-β-d-glucopyranosyl)-(1→6)-2,3,4-tri- O -acetyl-α-d-glucopyranoside (Acetylated 26)
^¹H NMR (500 MHz, CDCl₃): δ = 7.33-7.24 (m, 5 H, ArH), 5.43 (t, J = 10.0 Hz each, 1 H, H-3_A), 5.16 (t, J = 9.4 Hz each, 1 H, H-4_A), 5.03 (t, J = 9.5 Hz each, 1 H, H-3_B), 4.96 (dd, J = 7.9 Hz each, 1 H, H-2_B), 4.90 (t, J = 9.4 Hz each, 1 H, H-4_B), 4.88 (d, J = 3.6 Hz, 1 H, H-1_A), 4.82 (dd, J = 10.1, 3.6 Hz, 1 H, H-2_A), 4.55 (d, J = 11.9 Hz, 1 H, PhCH_2a), 4.52 (d, J = 7.9 Hz, 1 H, H-1_B), 4.48 (d, J = 11.9 Hz, 1 H, PhCH_2b), 3.94-3.89 (m, 2 H, H-6_abA), 3.65-3.61 (m, 1 H, H-5_B), 3.55-3.51 (m, 3 H, H-5_A, H-6_a,bB), 3.37 (s, 3 H, OCH₃), 2.06, 2.03, 1.98, 1.89 (4 s, 18 H, 6 COCH₃). ^¹³C NMR (125 MHz, CDCl₃): δ = 170.4, 170.1, 170.0, 169.7, 169.6, 169.4 (6 COCH₃), 137.9-128.1 (ArC), 101.2 (C-1_B), 96.8 (C-1_A), 73.9, 73.7, 73.3, 71.6, 71.2, 70.6, 69.7, 69.4, 69.2, 68.5, 68.3, 55.5 (OCH₃), 21.1 (2 C), 21.0 (2 C), 20.9 (2 C). ESI-MS (C₃₀H₄₀O₁₆): m/z = 679.2 [M + Na]⁺.