These results clearly show that reduction to 7 always occurs when the reaction conditions allow the presence of aldehyde 4 together with the initial condensation product, dianion 8 (Scheme 2).

• 这些结果清楚地表明还原反应条件发生时；7总是让在场的乙醛4初级产品与凝结；酸根8(方案2).