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Development of efficient and sustainable procedures for forming carbon-carbon and carbon–heteroatom bonds is the field of tremendous growth in recent decades. Discovery of new metal catalysts and preparation of new ligands contributed to a great extent to this process as a driving force in the construction of selective synthetic methods. However, development of environmentally benign new reagents are also equally obligatory. In the past, technical aspects and economic considerations were the main reasons for searching new chemicals. Increased awareness and concern for the environment, coupled with stringent environmental regulations, have become an additional factor. These regulations demand more nontoxic and stable chemical reagents. There is also a strong need for specific, selective, and effective reagents in the industrial process.
We have identified cyanated cyclohexadienes as stable and readily prepared reagents and have developed a Pd/Lewis acid (LA)-cocatalyzed operationally simple and effective method for highly regioselective transfer hydrocyanation of alkenes and alkynes using 1-methylcyclohexa-2,5-diene-1-carbonitrile as the reagent. The catalytic transfer hydrocyanation represents a clean and safe alternative to hydrocyanation processes using the toxic HCN gas. Also the reagent is utilized for the cyanation of aromatic halides.a We also developed a cross-coupling method for the regioselective β-alkenylation of 2,5-cyclohexadiene carboxylic acid derivatives to form ortho-alkenylarenes through in situ decarboxylation and concomitant aromatization. The carboxylic acid functionality is used as a traceless directing group for efficient and mild β-alkenylation.b Very recently, we have developed a highly diastereoselective Fe-catalyzed anaerobic Markovnikov-selective hydration of alkenes using nitroarenes as O-donors. As compared to known Mukaiyama hydration protocols, the nitroarene mediated process reported herein delivers the product alcohols with significantly higher diastereoselectivity.c A details of some of our results in this area will be presented.
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