Organic Puzzles: Classic and Modern Approach Helena Chechik-Lankin, Ph. D Student Under the supervision of Prof. Ilan Marek The Mallat Family Laboratory in Organic Chemistry, Department of Chemistry, Institute of Catalysis Science and Technology, The Lise Meitner-Minerva Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa 32 000, Israel Organic Chemistry is a branch of Chemistry that focuses upon the carbon containing compounds (organic compounds) and it is the largest and fastest growing branch of Chemistry. Organic molecules can often contain a higher level of structural complexity, so the synthesis of organic compounds has developed into one of the most important aspects of organic chemistry. Forming a carbon-carbon bond is the most fundamental operations in organic chemistry and the usual procedure for the synthesis of organic compounds is the stepwise creation of each individual bonds of the target molecule. Forming two carbon-carbon bonds in one reaction step is known. However, forming three or more bonds effectively in one reaction vessel is clearly a difficult task. Another fundamental operation in organic chemistry is the conversion of one functional group to another, since an activity or a bioactivity of the molecule is often dependent on the functional group. Combination of multiple carbon-carbon bond construction with formation of the desired functional groups in one reaction step represent an extremely severe challenge due to the multiplicity of reaction pathways available to reach polyfunctional molecules. Success, however, would provide rapid and efficient means for the transformation of simple molecules into structurally much more complex, useful compounds without isolating intermediates. It is obvious that this consept would allow the minimization of waste, amount of labor and time that are needed for achieving a desired product but more importantly, will provide new opportunitis to solve challenging problems on organic synthesis. Synthetic concept, based on multi-component reaction and applied in our laboratory, will be presented in the talk.