CHEM 309 Organic Chemistry II homework 10 With Completed Solutions- Boise State University

CHEM 309 Organic Chemistry II homework 10 With Completed Solutions- Boise State University Acid chlorides are the most reactive carboxylic acid derivatives. Provide curved arrows to complete t he following reaction mechanism for attack of a typical neutral nucleophile to an acid chloride. Remember the rules for drawing curved arrows: begin each arrow at a bond or lone pair (draw them in) and end each arrow at an atom or bond. lb) When neutral nucleophiles react with acid chlorides or anhydrides-the 2 reactive carboxylic acid derivatives-a tertiary amine base (such as NEt3) is often added. To demonstrate why, repeat the above reaction with the addition of NEt3 as a base (I've added some, but not all, of the structures to help you). In general, why would a chemist add NEt3? 2a) For the reasons hopefully demonstrated by lb, above, whenever a primary or secondary amine reacts with an acid chloride or anhydride, at least two equivalents of the amine are required (unless pyridine or a tertiary amine base are added). To ensure you understand this, provide curved arrows to complete the following reaction mechanism. As before, begin each arrow at a bond or lone pair (draw them in) and end each arrow at an atom or bond. 2b) What would you end up with if you didn't use two equivalents of the amine in the preceding pyridine-H+cr The following reactions are designed to demonstrate the importance of tosylates, mesylates, and triflates. This first reaction explains why PBr3 and TsCI are used. The second and third reaction sequences explain their differences. following is the acidic hydrolysis of an ester. Provide curved arrows to complete the following reaction mechanism. Remember the rules for drawing curved arrows: begin eacnarrow at a bond or lone pair (draw them in) and end each arrow at an atom or bond. /4b) While the saponification of an ester (i.e. basic hydrolysis) is irreversible, the acidic hydrolysis shown above is completely reversible. What would be practical things to do to convert reactants to products in high yield? What about Sa) The following is an intramolecular Claisen condensation (also called a Dieckmann condensat ion). Draw all of the intermediates and final product of this reaction. 0 0 ~ ~ONa cyclic and has cyclic and has cyclic HHQ 2O F' 1 0 o --- en_olate - only one C-0 - two C-O double - enolate ion - Pr~~~ct Chemical Formula: C14H2sO4 ~OH ron double bond bonds cyclic and has only one C-0 double cyclic and has two C-0 double bond (C14H250 4-) bonds (C11H1a03) o/ Cyclic enolate ion (C11H1103-) Final Product (C11H1a03) l½J Y -loA Sb) The Dieckman reaction for Sa used {CH3)iCHONa as a base. Why was this base used? What other based could have worked? Why? ' Page 3 of 4 0 /6) The following is an example of a malonic ester synthesis. Add the appropriate compounds to the indicated boxes. Note: contains two carboxylic acids Note: enol form of a carboxylic acid Note: Final carboxylic acid