The idea of working backwards from final target molecule to starting materials (usually via one or more intermediates) when designing a synthesis.
The development of this thought process is widely attributed to E. Corey of Harvard University, who was awarded the 1990 Nobel Prize in Chemistry.
” The first step is to see which bonds have changed between the products and reactants and we can see the bond colored in red.
Since only one bond changed, this is relatively “easy” example.
The reaction sequence for synthesis of tert-butanol from methylpropane, based on the retrosynthetic analysis above.
Retrosynthetic analysis is a technique for solving problems in the planning of organic syntheses.Thus, if we form two Br bonds to each of the carbons, we can then form the alkyne from 1,2-dibromo-3,3dimethylbutane.In the forward reaction, we can do this with a strong base such as sodium ethoxide (Na OEt) in ethanol to form the alkyne. To do this, we would have to carry out an addition reaction.Starting from an alkyne, remember that each double bond represents the presence of a pi bond that can be formed from an elimination reaction.So, think “what can we eliminate that would have resulted in pi bond formation?You will find that there are several different ways to complete the retrosynthesis, depending on which strategies you choose.University of East Anglia, UK Retrosynthetic Analysis Analysis of Complex Synthetic Problems; Terminology; Retrosynthetic Strategies; Goals and Subgoals; Computer-Assisted Retrosynthetic Analysis.We could think of forming an alkene from 3,3 dmethylbutanol by performing another E2 elimination (or dehydration) to remove the alcohol and anti-periplanar proton which would form 3,3-dimethylbutene.In the forward reaction, we can do this by activating the alcohol with tosyl chlroide to make a very good leaving group and then reacting with a strong base such as potassium tert-butoxide (t-Bu OK) to form the alkene. A three step synthesis from the alkyne product from a starting alcohol using reactions that are typically covered in the first few weeks of class.CMBI Advanced Retrosynthesis Lecture notes Disconnection Approach Introduction to chemical synthesis - Format: PDF Putting Reactions Together Synthesis and Retrosynthesis.Arizona State University, USA - Format: PDF Retrosynthesis The synthetic route to a target molecule: definitions and terms - Format: PDF Retrosynthesis Tutorial: Advanced Organic Chemistry - Format: PDF Retrosynthesis Lecture notes: designing organic syntheses.