NMR spectroscopic investigations of mixed aggregates underlying highly enantioselective 1,2-additions of lithium cyclopropylacetylide to quinazolinones.
NMR spectroscopic investigations of mixed aggregates underlying highly enantioselective 1,2-additions of lithium cyclopropylacetylide to quinazolinones.
复制标题
环丙基乙炔锂与喹唑啉酮的高度对映选择性 1,2-加成的混合聚集体的核磁共振波谱研究。
DOI：
10.1021/ja0105616
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发表时间：
2001
影响因子：
15
通讯作者：
Collum,DB
中科院分区：
文献类型：
--
作者：
ParsonsJr,RL;Fortunak,JM;Dorow,RL;Harris,GD;Kauffman,GS;Nugent,WA;Winemiller,MD;Briggs,TF;Xiang,B;Collum,DB
The solution structures of mixed aggregates derived from lithium alkoxides and lithium acetylides were investigated as part of a program to develop practical syntheses of quinazolinone-based nonnucleoside reverse transcriptase inhibitors. Low-temperature 6 Li, 13 C, and 15 N NMR spectroscopies reveal that mixtures of lithium cyclopropylacetylide (RCCLi), a (+)-carene-derived amino alkoxide (R* OLi), and lithium hexamethyldisilazide (LiHMDS) in THF/pentane afford a (RCCLi) 3 (R* OLi) mixed tetramer, a C 2-symmetric and asymmetric (RCCLi) 2 (R* OLi) 2 mixed tetramer, and a C 3-symmetric (RCCLi)(R* OLi) 3 mixed tetramer. Analogous mixtures of RCCLi/R* OLi in Et 2 O and Me 2 NEt also provide 3: 1, 2: 2, and 1: 3 mixed tetramers. The stereochemistry of aggregation is highly sensitive to the medium. The C 2-symmetric (RCCLi) 2 (R* OLi) 2 mixed tetramer is formed in Et 2 O, whereas the asymmetric isomer is formed in Me 2 NEt. LiHMDS in THF is shown to be an efficient proton scavenger without forming LiHMDS− RCCLi or LiHMDS− R* OLi mixed aggregates. LiHMDS− RCCLi mixtures form mixed aggregates in Me 2 NEt.
