SYNTHESES VIA-2-OXAZOLINES .1. FORMYLATION OF GRIGNARD REAGENTS IN PRESENCE OF HEXAMETHYLPHOSPHORAMIDE
SYNTHESES VIA-2-OXAZOLINES .1. FORMYLATION OF GRIGNARD REAGENTS IN PRESENCE OF HEXAMETHYLPHOSPHORAMIDE
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DOI：
10.1021/ja00725a069
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发表时间：
1970-01-01
影响因子：
15
通讯作者：
COLLINGT.EW
中科院分区：
文献类型：
--
作者：
MEYERS, AI;COLLINGT.EW
0 AI Vogel，“Elementary Practical Organic Chemistry，”Part 2，Longmans，绿色公司，纽约州纽约市，1962年。B M. Stiles和A. Sisti，J. Org. Chem.，25，1691（1960）。使用6以相同的方式进行反应。以51-90%的总收率得到醛8或其Cl氘代衍生物9。HMPA的使用是至关重要的，因为在没有HMPA的情况下，格氏试剂似乎与杂环氧10络合，导致环断裂，这是由于添加第二当量的格氏试剂，以优异的产率产生二烷基化氨基醇11。通过加入强溶剂化的HMPA使镁在10中的络合能力最小化，从而允许不间断地形成恶唑烷7.6。表I的检查表明，使用碘化恶唑啉鎓不能成功地使脂族格氏试剂甲酰化。在使用与HMPA络合的脂肪族格氏试剂的每种情况下，仅发生从5的质子提取。
0 AI Vogel,“Elementary Practical Organic Chemistry,” Part 2, Longmans, Green and Co., NewYork, NY, 1962. b M. Stiles and A. Sisti, J. Org. Chem., 25, 1691 (1960)." Reaction was carried out in the identical manner using 6. in aqueous oxalic acid led to the aldehyde 8 or its Cl deuterated derivative 9 in 51-90% overall yield for the two-step process. The use of HMPA is of critical importance since, in its absence, the Grignard reagents appear to complex with the heterocyclic oxygen 10 resulting in ring cleavage by virtue of ad-dition of a second equivalent of the Grignard, producing the dialkylated amino alcohol 11 in excellent yields. The complexing ability of magnesium in 10 is minimized by the addition of the strongly solvating HMPA, thus allowing the uninterrupted formation of the oxazolidine 7.6 Examination of Table I reveals that aliphatic Grignard reagents were not successfully formylated using the oxazolinium iodide. In every case using aliphatic Grignard reagents complexed with HMPA, only proton abstraction from 5 took place.