The suprafacial or antarafacial stereochemistry of the following sigmatropic reaction by order [ x , y ] is, Concept introduction: A sigmatropic rearrangement is a process in which a sigma-bonded substituent atom or group migrates across a pie electron system from one position to another. So, A sigmatropic reaction in organic chemistry is a pericyclic reaction wherein the net result is one σ-bond is changed to another σ-bond. Sigmatropic rearrangements are concisely described by an order term [ i , j ], which is defined as the migration of a σ-bond adjacent to one or more π systems to a new position (i-1) and (j-1) atoms removed from the original location of the σ-bond. [3] When the sum of i and j is an even number, this is an indication of the involvement of a neutral, all C atom chain. An odd number is an indication of the involvement of a charged C atom or of a heteroatom lone pair replacing a C = C double bond. Thus, [1, 5] and [3, 3] shifts become [1, 4] and [2, 3] shifts with heteroatoms, while preserving symmetry considerations. If the migrating group remains on the same face of the π system, the shift is known as suprafacial, while if the migrating group transfers to the opposite face is called an antarafacial shift.

Question

Part VII. The H-NMR of a compound with molecular formula C5 H 10 O2 is given below. Find the following: (a) The no. of protons corresponding to each signal in the spectra (6) Give the structure of the compound and assign the signals to each proton in the compound. a 70.2 Integration Values C5H10O2 b 47.7 C 46.5 d 69.5 3.6 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 Chemical Shift (ppm) 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8

Answer 1

Question

Chapter 30.7, Problem 7P

Interpretation Introduction

Interpretation:

The suprafacial or antarafacial stereochemistry of the following sigmatropic reaction by order [x, y] is,

Concept introduction:

A sigmatropic rearrangement is a process in which a sigma-bonded substituent atom or group migrates across a pie electron system from one position to another. So, A sigmatropic reaction in organic chemistry is a pericyclic reaction wherein the net result is one σ-bond is changed to another σ-bond.

Sigmatropic rearrangements are concisely described by an order term [i, j], which is defined as the migration of a σ-bond adjacent to one or more π systems to a new position (i-1) and (j-1) atoms removed from the original location of the σ-bond. [3] When the sum of i and j is an even number, this is an indication of the involvement of a neutral, all C atom chain. An odd number is an indication of the involvement of a charged C atom or of a heteroatom lone pair replacing a C = C double bond. Thus, [1, 5] and [3, 3] shifts become [1, 4] and [2, 3] shifts with heteroatoms, while preserving symmetry considerations.

If the migrating group remains on the same face of the π system, the shift is known as suprafacial, while if the migrating group transfers to the opposite face is called an antarafacial shift.

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