Synthesis of and from S-pyroglutamic acid. Regio- and diastereoselective ring opening of its derivatives
作者:Claus Herdeis、Andrea Aschenbrenner、Armin Kirfel、Franz Schwabenländer
DOI:10.1016/s0957-4166(97)00261-9
日期:1997.7
The pyroglutamic acid derivative 4 was converted through several steps into 2S,3R,4S-epoxyproline 8. Key steps of the reaction sequence were the stereoselective epoxidation of 4 to 5 and the chemoselective reduction of the amide group of 5 with concomitant transformation of the acetal moiety into the N-benzyl protecting group without oxirane ring opening. The air sensitive benzyl derivative was transformed
通过几个步骤将焦谷氨酸衍生物4转化为2 S,3 R,4 S-环氧脯氨酸8。反应顺序的关键步骤是的立体选择性环氧化4至5和化学选择性还原的酰胺基的5与缩醛部分的伴随转变成N-苄基保护基,而不环氧乙烷开环。将对空气敏感的苄基衍生物转化为稳定的N-Boc脯氨醇衍生物6。氧化6得到被保护的环氧脯氨酸衍生物7。解除保护7配备了对映体2 S,3 R,4 S-环氧脯氨酸8。环氧乙烷6或16的开环是在完全区域控制下用C,N,Cl亲核试剂完成的。叠氮基脯氨醇9用作合成Epiminoproline衍生物23的起始材料。