The result and discussion part of this book monitors a detailed in-depth mechanistic study with respect to the controlling effect of steric as well as electronic factors on photo-reactivity of mixed enones confined within semi cyclic framework. Proper justification in this area has been strongly supported by the exploratory research work exemplified by the author. In the review part of this book reader will also find a point to point discussion on photochemistry of enones, particularly in terms of alpha, bata- and beta, gamma-counterparts, in a very comprehensive manner starting from the very basic level to the advanced stage. Puckering of the geometry within this semi cyclic framework also becomes a constitutional factor to impose regio- as well as chemo-selectivity for the Wiitig reactions carried out on such kind of mixed enones. Content of the second chapter of this book has been purely focused on the effect of concentration on quantum yield. This typical uncommon effect has its selectiveness for a particular type of photo-product, the formation of which is very much dependent on the nature of the substitute pattern embedded with the substrate enone molecules.