CAJ | 학술논문

在L-脯氨酸催化的芳香醛与丙酮直接不对称aldol反应体系中添加二醇或二酚类助剂可有效提高反应活性.助剂的使用降低了该反应体系中L-脯氨酸的用量.特别是以邻苯二酚为助剂时,最佳反应条件下,仅用5mol％L-脯氨酸与1mol％助剂催化2-硝基苯甲醛与丙酮直接不对称aldol反应,aldol产物产率高达90％,对映选择性为80％.该反应产率比未加助剂条件下,L-脯氨酸用量为30mol％时的反应产率高.采用量子化学计算研究了助剂对该反应的促进作用.结果表明,助剂可与芳香醛的醛基形成氢键,从而活化醛基,提高反应效率.邻苯二酚结构中相邻的羟基能与底物芳香醛羰基的氧原子形成双氢键,大大活化了底物芳香醛的羰基.因此,该助剂可有效促进L-脯氨酸催化剂的直接不对称aldol反应.
재L-포안산최화적방향철여병동직접불대칭aldol반응체계중첨가이순혹이분류조제가유효제고반응활성.조제적사용강저료해반응체계중L-포안산적용량.특별시이린분이분위조제시,최가반응조건하,부용5mol％L-포안산여1mol％조제최화2-초기분갑철여병동직접불대칭aldol반응,aldol산물산솔고체90％,대영선택성위80％.해반응산솔비미가조제조건하,L-포안산용량위30mol％시적반응산솔고.채용양자화학계산연구료조제대해반응적촉진작용.결과표명,조제가여방향철적철기형성경건,종이활화철기,제고반응효솔.린분이분결구중상린적간기능여저물방향철탄기적양원자형성쌍경건,대대활화료저물방향철적탄기.인차,해조제가유효촉진L-포안산최화제적직접불대칭aldol반응.
The direct asymmetric aldol reaction of aromatic aldehydes with acetone catalyzed by L-proline was accelerated by the addition of diois or diphenols.The use of additives decrease the amount of L-proline needed and allowed the use of solvent free conditions.Catechol with two adjacent hydroxy groups on aromatic ring was the most efficient additive.Under the optimized conditions,5 mol％ L-proline with 1mol％ catechol gave excellent chiral selectivity (80％ ee value) with ＞ 90％ yield,which was higher than that obtained using 30 mol％L-proline without an additive.Computations indicated that the additive promoted the reaction by an intermolecular hydrogen bond between the hydrogen of the hydroxyl group and the oxygen of the carbonyl group,which activated the carbonyl group of the aldehyde.Catechol with two adjacent hydroxyl groups on the aromatic ring can form two hydrogen bonds with the oxygen of the carbonyl group on the corresponding aldehyde.Therefore,the combination of L-proline and catechol was very efficient in catalyzing the direct asymmetric aldol reaction and gave a high yield in a short time.