Deep-Dive Guides · Asymmetric Synthesis & Retrosynthesis

Asymmetric Synthesis & Retrosynthesis — the complete deep dive

Two disciplines answer "how would I make this?" Retrosynthesis is the logic of planning backward — breaking a target into simpler precursors by disconnections that map onto known bond-forming reactions, via idealised synthons and their real reagent equivalents.

Free extract — the opening section of the guide, in full.

0. Two ways of thinking about making molecules

Synthesis in the forward direction asks "what does this starting material do next?" Retrosynthesis runs backward: "what simpler precursor could give this target in one reliable step?" The backward arrow is the retrosynthetic (transform) arrow ⇒ (a double-shafted open arrow), and each backward step is a disconnection — an imagined bond cleavage that corresponds to a real forward reaction. Asymmetric synthesis then layers on the extra demand that a specific new stereocentre be set as one enantiomer.

The three questions to ask of any target: (1) Which bond(s) should I break (a "strategic" disconnection that most simplifies the molecule and maps to a good reaction)? (2) What synthons result, and what are their real reagent equivalents (including whether umpolung is needed)? (3) How is each stereocentre set — from the chiral pool, an auxiliary, a chiral reagent, or a catalyst — and what ee/de results? Answer these and a synthesis plan writes itself.

Read the rest of this guide

The remaining 9 sections — Retrosynthetic analysis — the grammar, Stereochemistry of synthesis — ee & de, The asymmetric toolbox — four strategic classes, Named asymmetric methods and more — are part of ChemVidya Full Access, along with the other guides, the books, the study notes and 6,000+ practice questions with worked solutions.

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