Two different alkenes are obtained in the E2 elimination reaction between 2-chloro-3-phenylbutane and sodium methoxide. The major product is the Zaitsev product.
(i) When one pure stereoisomer of 2-chloro-3-phenylbutane reacts, only one pure stereoisomer of the major product is obtained. For example, the product obtained when (2R,3R)-2-chloro-3-phenylbutane reacts is the stereoisomer with the methyl groups cis. Explain the reason behind this stereospecificity using a Newman projection of the transition state.
(ii) Predict the major product of elimination of (2S,3R)-2-chloro-3-phenylbutane using a Newman projection of the transition state.
(iii) By taking into account the results in part (i), predict the major product from elimination of (2S,3S)-2-chloro-3-phenylbutane.
Two different alkenes are obtained in the E2 elimination reaction between 2-chloro-3-phenylbutane and sodium methoxide. The major product is the Zaitsev product.
(i) When one pure stereoisomer of 2-chloro-3-phenylbutane reacts, only one pure stereoisomer of the major product is obtained. For example, the product obtained when (2R,3R)-2-chloro-3-phenylbutane reacts is the stereoisomer with the methyl groups cis. Explain the reason behind this stereospecificity using a Newman projection of the transition state.
(ii) Predict the major product of elimination of (2S,3R)-2-chloro-3-phenylbutane using a Newman projection of the transition state.
(iii) By taking into account the results in part (i), predict the major product from elimination of (2S,3S)-2-chloro-3-phenylbutane.