Word Count : 931

---

1,3-Dipolar cycloaddition is an important type of pericyclic reaction in which a 1,3-dipole reacts with an unsaturated compound such as an alkene or alkyne to form a five-membered heterocyclic ring. In organic chemistry, these reactions are particularly useful for the synthesis of pyrazoles. A 1,3-dipole is a three-atom system having four π-electrons distributed over three atoms and can be represented by resonance structures involving formal positive and negative charges. Diazo compounds, nitrile imines, azides and related species are common examples of 1,3-dipoles. For the preparation of pyrazoles, diazo compounds and nitrile imines are especially important. A [3+2] cycloaddition involves the combination of a three-atom 1,3-dipole with a two-atom π-component. The two components combine through their π-electron systems to produce a five-membered ring. When the dipole reacts with an alkene, the product initially formed is generally a dihydropyrazole, which can undergo oxidation or dehydrogenation to give an aromatic pyrazole. When an alkyne is used instead of an alkene, the [3+2] cycloaddition directly gives a pyrazole because the unsaturation required for aromaticity is retained in the newly formed ring. The general reaction of a diazo compound with an alkene can be represented as: Diazo compound + alkene → pyrazoline → pyrazole For example, diazomethane, CH₂N₂, behaves as a 1,3-dipole. It can undergo [3+2] cycloaddition with an alkene such as ethyl acrylate. The three atoms of the diazo group participate in the cycloaddition with the ______ ________ _____ ________ __________ _______ ___ ___ _____.
_______ _______ __________ ________ _____ ____ ________ _________ ____.
____ _______ _______ __________ _______ ____.
____ ____ ________ _____ _____ ____ __________.
_____ ______ ________ _________ _________ _______ ________ _____.
_________ ____ ______ _____ _________ ______ _______ __________ _______.
_____ ________ ___ ______ _____ _________ ___.
____ ____ ____ _______ ________ ______ ___ ______ _______ _____ ___ _________.
____ __________ __________ _________ ________ ___ __________ _____ ________.
___ ________ _____ _____ __________ _______ _________ ___ _________ ________ _______.
___ _____ __________ __________ ___ ______ ________ _____ _______ ____ ________ ________.
________ ______ ____ _________ ____ _____ _____ __________ ______.
_________ _____ _____ _________ ____ ____ ____ ___ ___ _______.
___ ______ _______ _____ _____ ____ ______ ____ ______ _______.
________ _________ ___ _________ ________ ___ _______ ______ ____ __________ ________ _____.
__________ ____ __________ _________ _______ ______ __________ ______.
___ ______ ___ ____ ___ __________ ____ ___ ___ ___.
_____ ____ _____ ________ _____ ________ ________ _______ _______ ____ ___.
______ _____ ______ _______ ______.
__________ _____ __________ __________ _________ ___ _____ _____.
____ ____ __________ _______ __________ _______ ________ _____ _________ _________.
___ ___ __________ __________ __________ _____ _____ ______.
________ _______ ______ ______ ______ ___ _________ _____ ________ _____ _________ __________.
_______ ______ _____ ________ ______ ___ ____ _____ __________.
________ ________ _____ ________ ______ _________ ___ __________ _______ ______ ____.
____ _________ _____ _____ __________ __________ ___ ________ ___ ________.
__________ __________ __________ ________ ________ _______.
________ ____ ___ ___ ____ __________ _________ ___ _____ ____ _____.
______ _______ _____ ____ ___ _____ __________ ____ ___.
_____ _________ _________ _________ ___ _____ ______ __________ _____.
______ _______ _________ _____ ____ __________.
_________ __________ ____ _____ _________ ____ ______ ____ ______ ___ ________.
_____ _____ ____ _______ ____ _________ _______ _________ _______ _________.
_____ _________ ________ _____ ________ _____ _________.
_____ ____ __________ ____ _________ ___ ________ _______.
________ __________ _________ _______ ________ _______ ________ ________ ________ ___ _________.
________ ________ _______ _____ _______ ____ _________ __________ ___ _________ ________.
__________ _____ _____ _______ _______.
___ __________ _____ _______ __________ ___ _______ _________ __________ _________ ___ ______.
___ __________ ______ ________ _________ ________ _____ _________.
________ _____ __________ _____ ________ _______ ___ ________.
_______ ____ _________ ______ ________ ______ _______ __________.
________ ______ _______ ________ _______.
_________ _________ ____ _________ ___ _______ ________ ________ __________ ___ _____ _______.
______ _______ ________ ___ __________ ______ ___ ___ __________.
___ ____ ______ ___ _______ ___.
_______ ____ ___ ____ _____ __________ _____ _________ _____.
________ ___ ___ _________ ___ __________ ______ _________.
__________ ________ _________ __________ ____ __________ __________ ________ _______ __________.
_________ ______ _________ ___ ________.
___ ____ ___ ______ ___ _________.
_______ ____ _________ _______ _____ _____ __________ _________ ______.
_______ ____ _______ ____ _____.
_____ ____ ___ _____ __________ _______ ____ _____ _____ ______ ____ ___.
_____ _______ ___ _____ _______ ____ _____ ___.
_______ ___ __________ _________ ______ __________ ____.
_______ ________ ________ _____ ______ ______ __________ ____ _____ ______ __________.
___ ________ _______ ______ _____ ________ _______ _____ __________.
_________ _____ ______ _________ ___ _______ _______ _________ ___ _____ ____.
________ _________ _________ ___ ___ ____ ____ ___ _____.
_______ _________ _____ _______ ____ ________ _________ ________ ______ _____.
____ _________ _______ ____ ______ ______ ___ ____ ___.
_______ _________ ___ _________ __________ ______.
_________ ____ ____ _______ _________ ___ _______ ____ _______ ______ ____ _________.
___ ______ ________ _________ _________ _________ ______ ______ ___.
_______ __________ ________ ___ ______ _____.
_________ _________ _____ _________ _______.
_____ ____ ________ ____ ______ ________ __________ _____.
____ _____ ___ ________ _________ ___ _________ _________ _________ _________.
____ _________ _________ ______ _________.
______ _________ ____ _____ __________.
________ ________ __________ ________ _____ _______ ____ _____.
_______ ___ __________ ___ __________ ___ _________ ___ ____ ____ ______.
_______ ________ ______ ___ ______ _________ _____ _________ ________ ________ ______ _________.
_______ _________ __________ ____ _________ ________ _________ ____.
______ _______ __________ _____ _______ ________ ______ ___.
_____ _________ ________ ____ _______ _____ ____ _________.
_______ ______ ____ ____ _____ ______ ______ ________ _________ _______.
____ _________ ________ __________ ______ _____ ______ _________ _________ __________ ______ __________.
____ ______ __________ _______.
Get Full Answer on WhatsApp