In a sigmatropic shift, a group migrates with its σ-bond within a π-framework (ene or polyene). The migration is accompanied by a shift in π-bonds. Suppose, we have a system like this, where, m= 1, 2, 3, 4 etc. During sigmatropic shift, group G with its sigma bond will migrate to this carbon and this migration will be accompanied by the shifting of pi-bonds to generate the rearranged product. In this lecture, we will focus only on [1,n] sigma tropic shift. Based on whether the migrating atoms is H or C, and n is 3, 5 or 7, [1,n]-sigmatropic shifts are classified as [1,3]-H shift, [1,3]-C shift, [1,5]-H shift, [1,5]-C shift, [1,7]-H shift, [1,7]-C-shift etc. In this lecture, rules governing these mirations have been discussed in detail.
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