(2S，3R，4S，5S)-2-甲氧基四氢-2H-吡喃-3，

Synthesis of (2S, 4S, 5S)-5-(t-Butoxycarbonylamino)-4-(t-Butyldimethylsilyloxy)-2-Isopropyl-7-Methyl Octanoic Acid

In an effort to produce renm mhibttory peptides, the preparation of (2 S ,4 S ,5 S )-5-( t -Butoxycarbonylamino)-4-( t -butyldimethylsilyloxy)-2-isopropyl-7-methyl octanotc acid, 15 , was carried out ( 1 ). This pseudo-dipeptide was used

Synthesis of (2R, 3R, 4R, 5S)-5-tert-Butyloxycarbonylamino-3,4-Dihydroxy-2-1sopropyl-3,4-O,O-Isopropylidene-6-CyctohexyI-Hexanoic Acid

The dipeptidic dihydroxyethylene isostere (27, 3R , 4R , 5S )-5-tert -butyloxy-carbonylamino-3,4-dihydroxy-2-isopropyl-3,4-O,O -isoprop-ylidene-6-cyclohexyl-hexanoic acid, 15 , is a representative building block of an important class

洪特规则

在原子轨道中填充排布的顺序为 1s 2s 2p 3s 3p 4s 3d4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d … 。 下面我们运用核外电子排布的三原则来讨论核外电子排布的几个实例。 氮 (N) 原子核外有 7 个电子，根据能量最低原理和保里不相容原理，首先有 2 个电子排布到第一层的 1s 轨道中，又有 2 个电子排布到第二层的 2s 轨道中。按照洪特规则，余下的 3 个电子将以相同的自旋方式分别排布到 3 个方向不同但能量相同的 2p 轨道中。氮