Benzoylated hexa-2,4-dien-4-olides from aldono-1,4-lactones: Stereoselective synthesis of dideoxyaldonolactone derivatives
作者:Carla Marino、Oscar Varela、Rosa M. de Lederkremer
DOI:10.1016/0008-6215(91)80012-c
日期:1991.11
of 4 gave stereoselectively the diastereoisomer having the d,l - threo configuration. Treatment of the lactonic disaccharide 2,3,5-tri- O -benzoyl-(2,3,5,6-tetra- O -benzoyl-β- d -galactofuranosyl)- d -galactono-1,4-lactone ( 7 ) with 20% triethylamine in dichloromethane afforded the diunsaturated derivative 8 as an E,Z mixture. Hydrogenation of 8 gave a 1:1 diastereomeric mixture of the 2( S ),4( R
摘要d-半乳糖醛酸酯(1a),d-葡萄糖醛酸酯(2a)和d-甘露聚糖-1,4-内酯(3a)的苯甲酰化,或对其相应的过苯甲酰化衍生物(1b,2b和3b)进行碱处理可得到相同的产品。2,6-二苯甲酰氧基-六-2,4-二烯-4-内酯(4)。取决于所采用的条件,获得化合物4为单一的4-Z异构体,或为4-E和4-Z非对映异构体混合物。丁烯内酯4来自双重β-消除过程,该过程似乎涉及ElcB机理,因为4的形成不受起始醛糖内酯中取代基的相对取向的影响。4的氢化选择性立体地得到具有d,1-苏构型的非对映异构体。内酯二糖2,3,5-三-O-苯甲酰基-(2,3,5,6-四-O-苯甲酰基-β-d-半乳糖呋喃糖基)-d-半乳糖醛-1的处理,用含20%三乙胺的二氯甲烷中的4-内酯(7)得到二不饱和衍生物8,为E,Z混合物。8的氢化得到2(S),4(R)和2(R),4(S)-3,5-二脱氧内酯[9(S,R)和9(R,S