At least one of these is meso there are at least 2 r

Info icon This preview shows pages 2–5. Sign up to view the full content.

View Full Document Right Arrow Icon
• at least one of these is meso • there are at least 2 (R) stereocenters represented in this pair true false true false true false G 1 G 2 G 1 &G 2 H 1 &H 2 I 1 &I 2 H 1 H 2 I 1 I 2 H Br CH 3 Br CH 3 H Br H CH 3 Br H H 3 C C C H 3 C OCH 3 HO H OH H C C H 3 C OH H HO H OCH 3 3 4 6 4 4 4 O O CH 2 CH 3 O E F X X X X X X X X X X X X X X X X X X X X X X X X arrows can go other way no partial no partial place E rel F = 3 points one curve, proper E A = 3 points
Image of page 2

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Name _______________________ Page 3 F.05.210E2 III. (24 points) The following molecule ( Compound J ) was prepared during the synthesis of epiquinamide, an alkaloid found in the skin of an Ecuadorean frog. N H H (H 3 C) 3 SiO H H O OCH 3 (a) Complete the following by filling in the 3 pairs of groups for the two lowest energy chair conformations for Compound J . The drawings should be completed so that the equilibrium constant for the process, as shown, is greater than 1. You only need to add the 6 groups shown in Compound J as you complete each drawing. K EQ >1 N N H H Draw a diastereomer of Compound J that would have a chair conformation which was more stable than either of the chair forms shown in part (a). You need only draw the planar form of the ring with its substitutents on dashes and wedges (as in the labelled drawing of Compound J at the top of the page (the chair form itself it not required). Compound J At a later stage in the synthesis of epiquinamide, Compound J was converted to Compound K . Using the stereochemical labels R , S , E , and Z , provide the proper stereochemical configurations for the sites indicated in Compound K . (b) (c) N C H HO H H O OCH 3 O Compound K 6 6 4 2 2 2 2 H H 3 CO O H (H 3 C) 3 SiO H O H 3 CO (H 3 C) 3 SiO H H H E S R S Important note about the ring nitrogen atom: When an sp3 hydridized nitrogen atom is part of a 6- membered ring undergoing the chair/chair conformational interconversion, the N-H bond ends up in the equatorial position regardless of which chair form is drawn. This is because the nitrogen atom, unlike any of the carbon atoms, can undergo re- hybridization that changes its stereochemistry. Your drawings in part (a) should clearly place the approriate substituent groups indicating the chair/chair interconversion of Compound J . 1) directionality of bonds 2) connectivity of groups 3) stereochemistry 4) proper conformation if (1) is bad: 0 if (2) is bad: -2 ea if (3) is bad: -2 ea if (4) is reversed: -2 everyone gets these 4 points b/c we messed up the problem; see next page for what it was supposed to be...
Image of page 3
Name _______________________ Page 3 F.05.210E2 III.
Image of page 4

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern