Atropisomerism in the 2-Arylimino-N-(2-hydroxyphenyl)thiazoline Series: Influence of Hydrogen Bonding on the Racemization Process

详细信息    查看全文

• 作者：Christian Roussel ; Nicolas Vanthuyne ; Mohamed Bouchekara ; Ayada Djafri ; Jos&eacute ; Elguero ; Ibon Alkorta
• 刊名：Journal of Organic Chemistry
• 出版年：2008
• 出版时间：January 18, 2008
• 年：2008
• 卷：73
• 期：2
• 页码：403 - 411
• 全文大小：167K
• 年卷期：v.73,no.2(January 18, 2008)
• ISSN：1520-6904

文摘

BLE>D=jo701756un00001>bscribe/journals/joceah/73/i02/figures/jo701756un00001.gif" ALIGN="left" HSPACE=5>A series of original atropisomeric iminothiazolines 1 in which X = OH or (and) Y = OH were preparedfrom the corresponding methoxy precursors. The resolution of the atropisomeric enantiomers on chiralsupport is reported, and the barriers to enantiomerization are given. These barriers were determined eitherby off-line racemization studies or by treatment of the plateau-shape chromatogram during chromatographyon chiral support. When X = OH, the barriers are quite low due to the development of a hydrogen bondbetween the proton of the OH group and the nitrogen of the imino group. For these compounds, plateaushape chromatograms were obtained during HPLC on chiral support. DFT calculations confirmed theoccurrence of hydrogen bonding all along the rotation process and produced calculated barriers in closeagreement with the experimental data. Compound 1i (OH, OH) in which both X and Y are hydroxygroups was particularly easy to prepare by demethylation with BBr₃ of the dimethoxy precursor. Sincethe above-mentioned precursor is readily available from N,N'-bis(2-methoxyphenyl)thiourea and1-chloropropan-2-one, 1i (OH, OH) is a good candidate for further functionalization. Atropisomerism ina 12-membered bridged bisether prepared from 1i (OH, OH) is reported as an illustrating example.