Gamma(y)-amino butyric acid (GABA) is a neurotransmitter (a chemical that is used to send signals from one neuron to another) of the mammalian central nervous system. In order to understand how GABA works, conformationally restricted analogues, such as compound 1, have been made. During a synthesis of compound 1, compound 2 was subjected to allylic bromination using NBS and a radical initiator (AIBN) instead of light (Aust. J. Chem. 1981, 34, 2231-2236). H₂N. GABA CO₂H H₂N CO₂H dddd solddd 2 Modify the structures given below to draw all eight possible allylic bromides that can be formed when compound 2 undergoes allylic bromination, considering all possible regiochemical and stereochemical outcomes. You can use the single bond tool to add/remove pi bonds. CH₂ CO₂Et

1. Bicyclic keto compounds such as camphor react predictably with nucleophiles according to steric influences; this effect has been termed steric approach control. In contrast, the reaction of nucleophiles with simple acyclic and monocyclic keto compounds are influenced primarily by thermodynamic factors; this effect has been termed product development control. Given the following reaction, predict the identity of the major product and provide a rationale for your selection. ОН NABH4 t-Bu. t-Bu t-Bu. ELOH 1 2

(c) The sedative, R-thalidomide, was once used to address symptoms of morning sickness in expectant mothers, however, when it was discovered that S- thalidomide causes deformities in infants, the use of R-thalidomide as a sedative was discontinued. With the help of a reaction mechanism, explain why enantiopure R-thalidomide can not be safely used as a sedative without affecting infants

(4) Provide the reagents necessary to carry out the following synthesis. + enantiomer (A) (1) (i) BH3, (ii) H₂O2, NaOH; (2) NaOEt JATOT (B) (1) (i) BH3, (ii) H₂O2, NaOH; (2) TsCl, pyridine; (3) KOC(CH3)3 (C) (1) H3O+, (2) TsCl, pyridine, (3) KOC(CH3)3 (D) (1) HBr (no peroxides); (2) NaOEt

The Dess–Martin reaction reacts an alcohol with the Dess–Martin periodinane. The first step displaces one of the acetate groups on the periodinane with the alcohol. A base then deprotonates one of the alpha protons, forming a new carbonyl bond, iodinane and acetic acid. The oxidation stops at this stage to give the aldehyde. Both Swern and Dess–Martin conditions will also convert a secondary alcohol to a ketone. Now apply what has just been discussed. Draw the major organic product.

Spirocyclic compounds, such as compound 3, are made and used by insects for the purposes of communication. The first step of a synthesis of compound 3 involves treatment of (S)-1,2-epoxypropane (compound 1) with lithium acetylide, followed by acid workup, to give compound 2, as shown below (J. Org. Chem. 2005, 70, 3054-3065). Identify the structure of compound 2 and provide a mechanism for its formation. (Hint: The carbon-lithium bond reacts in a way that is similar to the carbon-magnesium bond of a Grignard reagent.) 1 13.17 a 1) Li—= 2) H₂O+ нас!!!!!! C5H8O Edit Drawing 2 Ž Modify the given structure of the starting material to draw the major product. an 3