An organocatalytic, asymmetric, double-Michael strategy has been developed employing trans-α-cyano-α,β-unsaturated ketones for the synthesis of pentasubstituted tetrahydrothiopyrans bearing a quaternary center. A proline-derived bifunctional thiourea was found to be the most effective catalyst for this reaction. With 10 mol% of catalyst, good yields and good to high diastereomeric ratios, as well as excellent enantioselectivities, were obtained with a variety of tetrahydrothiopyrans under mild reaction conditions.

中文翻译：

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通过双迈克尔反应有机催化不对称合成带有四元中心的五取代四氢噻喃

使用反式-α-氰基-α,β-不饱和酮开发了一种有机催化、不对称、双迈克尔策略，用于合成带有四元中心的五取代四氢噻喃。脯氨酸衍生的双功能硫脲被发现是该反应最有效的催化剂。使用 10 mol% 的催化剂，在温和的反应条件下，使用各种四氢噻喃可以获得良好的产率和良好的非对映体比例以及出色的对映选择性。