Helppppp!!!! =] So I am doing some practice questions and I cannot understand th

Question

Helppppp!!!! =] So I am doing some practice questions and I cannot understand this one. I was given the question in the box (see attached) and asked to give the maj/min products. I know it is tertiary so it cant be SN2 and a bulky base so it must be E2. When I draw the products the major I get is with the stars and I checked using the newman projection to make sure I and H were anti periplanar and still got the same major and minor products. The book has it the opposite way around where the major 1-2 carbon has the double bond and the minor is the 2-3 carbon double bond. Can you tell me what I am doing wrong? If it makes any difference, this question is from orgo as a second language: first semester topics Q 10.36

Explanation / Answer

Actually there is a minute mistake in your Newman projection. To the anti-periplanar side of I there should be a methyl group which will impede the formation of double bond in 2-3 carbon. And hence there will be extraction of acidic H from primary carbon (which is attached to the carbon that is bonded with the carbon attached with iodine) to form a double bond at 1-2 carbon. Thus double bond at 1-2 carbon becomes the major product and on rotation around the single bond 2-3 carbon, there may remain a possibility of the formation of double bond at 2-3 carbon, therefore it serves as the minor product.

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