Organic hydrides
brief introduction
Lithium hydride, lithium aluminum hydride, sodium borohydride, triethyl lithium borohydride (Super Hydride)/sodium/potassium, tris butyl lithium borohydride (L-Selectride)/sodium/potassium (K-Selectride), Lithium Trisiamylborohydride (LiBSia3H) 60217-34-7, tri-tert-butyloxy aluminum hydride solution, 77299-63-9, Diisobutylaluminum hydride, DIBAL， Borane tetrahydrofuran, amino borane, and other metal hydrides are widely used as reducing agents and sources of negative hydrogen ions in inorganic and organic synthesis, as well as as as hydrogen storage materials in daily production and life. Metal hydride reducing agents can reduce substituted halogenated compounds to alkanes, aldehydes, ketones, epoxidimides, alcohols or amines, carboxylic acid derivatives such as esters, nitriles, and other derivatives to certain hydrocarbon substituted metal compounds. They have the advantages of mild reaction conditions, fewer side reactions, and high yields, demonstrating good chemical and stereoselectivity. In the synthesis of complex natural products and drug molecules, there are more advantages compared to other reduction methods.
Application examples
1. Reduce halogenated compounds to the corresponding alkanes (reaction formula A, B）， And deuterium substitution experiments indicate that the reduction reaction undergoes a clear SN2 substitution mechanism (reaction formula B). Additionally, OTs, OMs, and other substituents can also be reduced.
2. To reduce epoxy to alcohol, in the following example, the selectivity of triethylborohydride lithium is much higher than that of tetrahydroaluminum lithium.
3. Selective reduction of aldehydes and ketones to corresponding alcohols. In the reduction of α - cyclohexanone, a highly selective product (reaction formula D) is obtained; And in the presence of both aldehydes and ketones, aldehydes can be preferentially reduced to the corresponding primary alcohol (reaction formula E). Among them, Lithium trisiamylborohydride (LiBSia3H) exhibits better selectivity. Taking other substituted cyclohexanones as an example, the reduction of various hydrides is summarized in Table 1.
4. Selective reduction of carboxylic acids and their derivatives. It is possible to selectively reduce ester groups in the presence of other reducible groups.
5. Other uses. Hydrides can also transfer negative hydrogen ions to other transition metal organic compounds, forming new M-H compounds and selectively removing methyl groups.
参考文献
l三乙基硼氢化锂，Marek Zaidlewicz，Herbert C.Brown，有机合成试剂百科全书，2001年
l Krishnamutthy，S.Schubert R.M Brown，H，C，J.，美国化学。Soc 1973，958486
l JACS，1973
