Synthesis of 3-fluoropyrrolidines and 4-fluoropyrrolidin-2-ones from allylic fluorides.
Synthesis of 3-fluoropyrrolidines and 4-fluoropyrrolidin-2-ones from allylic fluorides.
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DOI：
10.1002/chem.201201576
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发表时间：
2012-10
期刊：
影响因子：
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通讯作者：
L. E. Combettes;M. Schuler;Rakesh Patel;Baltasar Bonillo;B. Odell;A. Thompson;T. Claridge;V. Gouverneur
中科院分区：
文献类型：
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作者：
L. E. Combettes;M. Schuler;Rakesh Patel;Baltasar Bonillo;B. Odell;A. Thompson;T. Claridge;V. Gouverneur
通过5-exo-trig碘环化反应，从带有侧挂氮亲核试剂的烯丙氟化物制备了各种3-氟吡咯烷和4-氟吡咯烷-2-酮。这些工作台稳定的前体可通过相应的烯丙基硅烷的亲电加成而获得。烯丙基氟取代基的存在诱导碘环化后的顺式立体控制，对于所有N-甲苯磺酰基-3-氟戊-4-烯-1-胺和酰胺，非对映异构体比率为10：1至> 20：1。立体控制的意义和水平惊人地类似于相应的碘环化的结构相关的烯丙基氟化物轴承挂起的氧亲核试剂。这些结果表明，在环闭合时观察到的顺式选择性涉及I（2）-π络合物与位于内部的氟。
Various 3-fluoropyrrolidines and 4-fluoropyrrolidin-2-ones were prepared by 5-exo-trig iodocyclisation from allylic fluorides bearing a pending nitrogen nucleophile. These bench-stable precursors were made accessible upon electrophilic fluorination of the corresponding allylsilanes. The presence of the allylic fluorine substituent induces syn-stereocontrol upon iodocyclisation with diastereomeric ratios ranging from 10:1 to > 20:1 for all N-tosyl-3-fluoropent-4-en-1-amines and amides. The sense and level of stereocontrol is strikingly similar to the corresponding iodocyclisation of structurally related allylic fluorides bearing pending oxygen nucleophiles. These results suggest that the syn selectivity observed upon ring closure involves I(2)-π complexes with the fluorine positioned inside.