Question

Problem set 2: (25 marks) In this problem you have to elucidate the structure of product B. A substrate A (structure shown in scheme 1) which was subjected to two consecutive reactions as shown in scheme 1 below to give the product B of molecular formula CsH14Br2. Provide the structure for Product B based on the NMR data provided (attachment 2: Problem set 2). (The 1H NMR and 13C NMR of starting substrate A has been provided for reference purpose only) 1. MnO2, CHCI3, rt, 24 h OH CgH14Br2 Product B 2. CBr4, PPH3, DCM, 2 h, rt Substrate A Scheme 1 The spectra for product B was recorded on 400 MHz instrument. Elucidate the structure based on the NMR spectra provided: 1H, 13C, DEPT 135, DEPT 90. In your answer include: 1H spectral details (Chemical shift values, Coupling pattern and constants with unit, Number of proton integration and assignment of peaks as aromatic/alkene/... etc and any other remarks) 13C spectral details (Chemical shift values, type [C, CH2, CH3] and assignment). Draw the proposed structure and assign 1H and 13C chemical shift values with brief justification. ii) iii) Reference 1H NMR and 13C NMR spectra of starting material, substrate A OH 12 7.5 7.0 6.5 s.5 6.0 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1-5 1.0 0.5 Ppm 230 200 210 10 pem 2. 1H NMR of Product B (whole spectra) 2 sha Ndrssc od 20128710 2 59299 093 86 - T 35 Cheme S pp 25 20 15 10 55 05 65 60 50 80 w- 2. 1H NMR of Product B expanded (to reveal splitting 5.4 ppm to 5.9 ppm) shaNG RSS 001 001 tr esp wwwwwwwweeTT 540 wwww ses Che S ppm 535 530 575 570 s0 545 5.50 3. 1H NMR of Product B expanded (to reveal splitting 16 ppm to 2.1 ppm) shaNGIRSS 001.001 tr esp- 201 287 107 205 190 200 190 1 65 2.10 175 170 1 60 Chencal Sppm 4. 1H NMR of Product B expanded (to reveal splitting, 0.8 to 1.15 ppm) 2sha NG1R55001.001 tr esp 299 290 115 1 10 1 05 100 035 0.30 Chemcal Sht (ppm S. 13C NMR of Product B P sha NGIRS5.Dc02 001 1r p t60 140 120 Cher Sht (ppm g- 60- z0zEi 6. DEPT 135 of Product B psha NGIR55.004 001.1r esp TTETET 180 160 120 100 Checal Spg 40 20 140 7. DEPT 90 of Product B sna NG1R56 004 001 1r esp 180 160 140 Chemical Sht ppm SI- ESi- Crzz- LKI-