Diazomethane is a quite interesting compound that is used in many synthetic transformations. So, before going over these reactions, let’s draw the structure of diazomethane by showing the corresponding resonance structures: The main theme that gives the characteristic … Read more
We have learned in the discussions about Grignard reagents that they must be used in dry conditions and aprotic solvents because the organometallics are strong bases and are quenched in any medium with acidic protons: So, if we … Read more
In the Wolff rearrangement, an α-diazocarbonyl compound is converted into a ketene by the loss of nitrogen, which is facilitated by a 1,2-shift (1,2-rearrangement): As a reminder, ketenes are highly reactive species that contain a C=C=O functional group: … Read more
The Structure of Ketenes Ketenes are compounds containing a C=C=O functional group: The structure and geometry of ketenes are similar to those of allenes, where three carbon atoms are connected via double bonds. As much as the central … Read more
The Arndt-Eistert reaction is used for extending the carbon chain of carboxylic acids by one carbon atom: The extra carbon is introduced via diazomethane (CH2N2), which is quite nucleophilic and, upon reacting with an acid chloride, forms a … Read more
We have discussed earlier that esters can be hydrolyzed under acidic or basic conditions to give carboxylic acids and alcohols. Lactones behave in an analogous way, except that being cyclic esters, their hydrolysis leads to ring opening and … Read more
We have seen earlier that esters react with two equivalents of Grignard reagent to form tertiary alcohols after acidic workup. The reaction occurs through two successive nucleophilic additions: the first addition forms a tetrahedral intermediate that collapses by expelling the … Read more
We have seen that amides can be hydrolyzed to carboxylic acids and amines under acidic or basic conditions. Lactams are cyclic amides, and the amino and carboxyl groups are part of the same molecule; therefore, the products of … Read more
We have seen that the reduction of lactones with LiAlH₄ proceeds through ring opening and ultimately gives diols after two consecutive hydride additions. A very similar hydride reduction can also be applied to lactams, although the outcome and key mechanistic … Read more
We have seen that esters can be reduced to alcohols by lithium aluminum hydride (LiAlH₄) through two consecutive additions of hydride ions to the carbonyl carbon. The mechanism starts with nucleophilic attack of hydride on the ester carbonyl, … Read more
