22. Robinson Annulation-Mechanism and Shortcut, Alpha Halogenation of Enols and Enolates Practice Problems, Aldol Reaction – Principles and Mechanism, Aldol Condensation – Dehydration of Aldol Addition Product, Aldol Addition and Condensation Reactions – Practice Problems, Crossed Aldol And Directed Aldol Reactions, Crossed Aldol Condensation Practice Problems, Acetoacetic Ester Enolates Practice Problems, Michael Reaction: The Conjugate Addition of Enolates, Robinson Annulation, Shortcut, and Retrosynthesis, Dieckmann condensation – An Intramolecular Claisen Reaction, Crossed Claisen and Claisen Variation Reactions. The reaction works mostly for five- and six-memebred ring as these are the most stable. Retrosynthetic Analysis in Robinson Annulation . Luckily these bonds are arranged such that the bond cleavage is easily achieved by drawing a line that bisects both bonds: The retrosynthesis of robinson annulation forms a ketone compound by breaking several carbon-carbon bonds. So, what happens is the Michael product undergoes an intramolecular aldol condensation to form a new six-membered ring. Advanced Organic Chemistry. California Subject Examination for Teachers - Preparation Resources, Discover the Physical Sciences Breakfast Lecture Series, Orange County Alliance for Community Health Research, http://ocw.uci.edu/courses/chem_125_advanced_organic_chemistry.html, http://ocw.uci.edu/collections/open_chemistry.html, Creative Commons Attribution 3.0 United States License, Chem 125. This required the aldol ring to be cleaved and the nucleophile to … Diels-Alder; Robinson Annulation.View the complete course: http://ocw.uci.edu/courses/chem_125_advanced_organic_chemistry.htmlInstructor: James S. Nowick, Ph.D. License: Creative Commons BY-NC-SATerms of Use: http://ocw.uci.edu/info.More courses at http://ocw.uci.edu. In the previous post, we talked about the Michael reaction which is a conjugate-addition reaction of doubly stabilized enolates such as malonic ester, acetoacetic ester and the like with ɑ, β-unsaturated carbonyl compounds: One important variation of the Michael addition is the Robinson annulation, which is commonly used in organic synthesis to prepare a ring through an aldol condensation of the Michael addition product. Required attribution: Nowick, James S., Advanced Organic Chemistry 125 (UCI OpenCourseWare: University of California, Irvine), http://ocw.uci.edu/courses/chem_125_advanced_organic_chemistry.html [Access date]. Description: The course builds upon the concepts and skills learned in a typical yearlong sophomore-level organic chemistry class. Diels-Alder; Robinson Annulation. Topics include: The Chemical Literature and Databases; Stereochemistry and Structural Organic Chemistry; Synthetic Organic Chemistry; Mechanistic and Physical Organic Chemistry; NMR Spectroscopy. Retrosynthetic Analysis. Check this comprehensive set of alpha carbon chemistry questions: Enolates in Organic Synthesis – a Comprehensive Practice Problem. You can also subscribe without commenting. Retrosynthetic Analysis. Organic Chemistry Study Materials, Practice Problems, Summary Sheet Guides, Multiple-Choice Quizzes. 22. Diels-Alder; Robinson Annulation by Nowick, James) is licensed under a Creative … It combines two reactions: the … I call it the α-β orientation: To determine the starting materials of a Robinson annulation, you need to cleave the C=C bond and the bond between the β carbon and the carbon to which it is bonded. The Robinson Annulation is a useful reaction for the formation of six-membered rings in polycyclic compounds, such as steroids. This work (Chem 125. To determine the starting materials of a Robinson annulation, you need to cleave the C=C bond and the bond between the β carbon and the carbon to which it is bonded. One shortcut to predicting the product of a Robinson annulation reaction is to put the β carbon of the Michael acceptor next to the ɑ position of the Michael donor and the ɑ carbon of the Michael acceptor next to the carbonyl of the Michael donor. This may sound too much for a shortcut, but really, all you do is place ɑ and β carbons of the two molecules next to each other to make new bonds. Organic Chemistry 1 and 2 Summary Sheets – Ace your Exam. Let’s put together a complete mechanism for the Robinson annulation: The last step, after the aldol condensation, is an E1CB elimination and the mechanism for this reaction is covered in the aldol condensation post. Advanced Organic Chemistry. It’s all here – Just keep browsing. Index of Topics:0:01:23 Retrosynthetic Analysis0:05:17 Problem 8.70:11:18 Robinson Annulation0:21:28 Proposed Synthesis for Problem 8.70:41:45 Danishefsky Synthesis. After this connect the carbons with a single and double bond respectively. Notify me of followup comments via e-mail. Luckily these bonds are arranged such that the bond cleavage is easily achieved by drawing a line that bisects both bonds: Need some additional practice problems? Retrosynthetic Analysis. UCI Chem 125 Advanced Organic Chemistry (Spring 2016)Lec 22. License: Creative Commons Attribution 3.0 United States License. Advanced Organic Chemistry (Chem 125) is part of OpenChem: http://ocw.uci.edu/collections/open_chemistry.htmlThis video is part of a 28-lecture junior/senior-level undergraduate-level course titled "Advanced Organic Chemistry" taught at UC Irvine by Professor James S. Nowick.