Davis T M, Lowary T L
Department of Chemistry, The Ohio State University, Columbus 43210, USA.
Carbohydr Res. 2000 Feb 25;324(3):210-7. doi: 10.1016/s0008-6215(99)00296-7.
Treatment of 3,7-anhydro-4,5,6,8-tetra-O-benzyl-1,2-dideoxy-D-glycero-D-galacto-oct-1 -ynitol (beta-D-mannosyl acetylene, 1) with 5 equivalents of n-butyllithium at either 0 or -78 degrees C resulted in the elimination of benzyl alcohol to yield 3,7-anhydro-5,6,8-tri-O-benzyl-1,2,4-trideoxy-D-arabino-oct-3-en-1-yn itol (glycal acetylene, 3) as the major product. Additional studies showed that 3 is also produced from two isomers of 1 with alpha-D-mannosyl and beta-D-glucosyl stereochemistry, but in lower yields. Furthermore, substrates in which the acetylene moiety is replaced by either a methyl or phenyl group do not produce a glycal product under these conditions. Finally, treatment of 1 with phenyllithium provides 3 in low yield. Deuterium labeling studies suggest that the reaction proceeds through an E2, rather than an E1cB, mechanism.
在0℃或-78℃下，用5当量的正丁基锂处理3,7-脱水-4,5,6,8-四-O-苄基-1,2-二脱氧-D-甘油-D-半乳糖辛-1-炔醇（β-D-甘露糖基乙炔，1），会消除苄醇，生成3,7-脱水-5,6,8-三-O-苄基-1,2,4-三脱氧-D-阿拉伯糖辛-3-烯-1-炔醇（糖炔，3）作为主要产物。进一步的研究表明，具有α-D-甘露糖基和β-D-葡萄糖基立体化学的1的两种异构体也能生成3，但产率较低。此外，在这些条件下，乙炔部分被甲基或苯基取代的底物不会生成糖炔产物。最后，用苯基锂处理1可得到低产率的3。氘标记研究表明，该反应通过E2机理进行，而不是E1cB机理。
