Highly Stereoselective and Stereodivergent Synthesis of Four Types of THF Cores in Acetogenins Using a C<sub>4</sub>-Chiral Building Block
作者:Naoyoshi Maezaki、Naoto Kojima、Mikito Asai、Hiroaki Tominaga、Tetsuaki Tanaka
DOI:10.1021/ol026393j
日期:2002.8.1
[reaction: see text] Four stereoisomers of the THF cores, synthetic intermediates of acetogenins, have been synthesized with high diastereoselectivity by asymmetric alkynylation and subsequent stereodivergent THF ring formation. The asymmetric alkynylation of alpha-oxyaldehyde with (S)-3-butyne-1,2-diol derivatives (C4-unit) gave good yields of syn and anti adducts with >97:3 dr and 94:6 dr, respectively
[反应:见正文] THF核的四个立体异构体,即原味素的合成中间体,已通过非对称炔基化反应和随后的立体发散THF环形成而以高非对映选择性合成。α-乙醛与(S)-3-丁炔-1,2-二醇衍生物(C4-单元)的不对称炔基化反应可分别以> 97:3 dr和94:6 dr的高收率合成正反加合物。通过一锅四氢呋喃的形成或分子内威廉姆森合成,将这些加合物转化为四种类型的四氢呋喃化合物。