Synthesis of C 2 -symmetric guanidino-sugars as potent inhibitors of glycosidases
作者:Yves Le Merrer、Laurence Gauzy、Christine Gravier-Pelletier、Jean-Claude Depezay
DOI:10.1016/s0968-0896(99)00294-1
日期:2000.2
A series of enantiomerically pure C-2-Symmetric guanidino-sugars was synthesized from D-mannitol. The first method described involves direct opening of a bis-epoxide by guanidine, whereas the second one deals with a mercury-catalyzed transformation of a cyclic thiourea into a N,N,N"-trisubstituted guanidine as a key step. The biological activity of these compounds towards several glycosidases has been evaluated. One of them (5) was found to selectively inhibit alpha-L-fucosidase of bovin kidney (2.8 mu M). (C) 2000 Elsevier Science Ltd. All rights reserved.
Cyclopropenium-Activated Cyclodehydration of Diols
作者:Brendan D. Kelly、Tristan H. Lambert
DOI:10.1021/ol102980t
日期:2011.2.18
The dehydrative cyclization of diols to cyclic ethers via cyclopropenium activation is described. Using 2,3-diphenylcyclopropene and methanesulfonic anhydride, a series of 1,4- and 1,5-diols are rapidly cyclized to furnish tetrahydrofurans and tetrahydropyrans in high yield. Eleven total substrates are shown, including a gram scale cyclization of a diterpene derivative.
Direct selective and controlled protection of multiple hydroxyl groups in polyols via iterative regeneration of stannylene acetals
作者:Alessandro B.C. Simas、Angelo A.T. da Silva、Tarcizio J. dos Santos Filho、Pedro T.W. Barroso
DOI:10.1016/j.tetlet.2009.03.114
日期:2009.6
A direct selective protection (O-benzylation) of two or more hydroxyl groups in polyols displaying diverse Structural patterns was made possible by the establishment of conditions that enable an efficient turnover for the Bu2Sn group, initially at the corresponding stannylene acetals (only similar to 1.0 mol equiv of Bu2SnO was employed). It was also demonstrated that one might exert control over the number of protected groups, by means of appropriate tuning of reaction conditions. The feasibility of a substoichiometric (tin source) catalytic protocol was demonstrated as well. (C) 2009 Elsevier Ltd. All rights reserved.