New Applications of 1,5-Hydrogen Atom Transfer Reactions: Self-Oxidizing Protecting Groups
作者:Dennis P. Curran、Hosung Yu
DOI:10.1055/s-1992-34173
日期:——
Three new alcohol protecting groups are introduced: o-bromobenzyl, o-bromo(methylenedioxy)benzyl, and o-bromotrityl. Removal of these protecting groups under reductive conditions with tributyltin hydride is coupled with an oxidation of the substrate to produce directly an aldehyde or ketone. This oxidation occurs by 1,5-hydrogen transfer, followed by ß-fragmentation. For example, treatment of the o-bromobenzyl ether of 3-phenyl-1-propanol with tibutyltin hydride at 0.001 M (80°C) directly produces 3-phenyl-1-propanal. An application to the selective oxidation of primary alcohols in the presence of secondary alcohols is also introduced.
Nickel-Catalyzed Selective Reduction of Carboxylic Acids to Aldehydes
作者:Andrei V. Iosub、Štefan Moravčík、Carl-Johan Wallentin、Joakim Bergman
DOI:10.1021/acs.orglett.9b02779
日期:2019.10.4
The direct reduction of carboxylicacids to aldehydes is a fundamental transformation in organic synthesis. The combination of an air-stable Ni precatalyst, dimethyl dicarbonate as an activator, and silane reductant effects this reduction for a wide variety of substrates, including pharmaceutically relevant structures, in good yields and with no overreduction to alcohols. Moreover, this methodology
A facile and efficient reduction of aromatic and aliphatic acyl chlorides to their corresponding aldehydes in the presence of Sm(0)/Bu3P has been developed with broad scope. This method prevents over reduction of products, that is, the over-reduction of aldehydes to alcohols.
在广泛存在的范围内,已经开发了在Sm(0)/ Bu 3 P存在下将芳香族和脂肪族酰氯轻松有效地还原为相应的醛的方法。该方法防止产物过度还原,即防止醛过度还原为醇。