2_21_2001

2_21_2001 - NAME: (please PRINT) Chemistry 1303 Exam 2...

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Unformatted text preview: NAME: (please PRINT) Chemistry 1303 Exam 2 February 21, 2001 0 Value Total Score 35 13 13 15 15 6 + 15 + 4 + 2 27 90 I. Provide the major organic product(s) from the following transformations. Indicate stereochemistry where appropriate. ¢ u.O-};BH,THF ‘-—-——-—> (a) 2, HzOz. HO' 3. LAH, £110 1. “30* (b) -——-> 0 2. enwg), HCI Q I. MM, 020 2. CH2 = PPb3 1, P00, 0120!: (d) 2. HOW”. , H20 T": l. 05 , *W‘ (f) ’ H 2. Zn / HOAc H' 03 Ed 3- HZN'NHZ 4-. K0“, HONDWOH A C02Me * (g) “t H _—-——> 150). 11. Starting with compound 1 below and using any reagents of your choosing, devise a short synthesis of bicyclic target 2. OH ——> OJ 0 o 1 2 III. The process of "transketalization" involves conversion of one ketal to another, as in going from 3 to 4, below. This can also be used to convert 3 to dithioketal 5. Provide a mechanism for the 3 to 5 conversion. OEt H+ OMe HS(CH2)3SH s/j OEt ‘—— OMe -——> S EtOH, A BFa 4 5 IV. Compound X has a molecular weight of 126, and a molecular formula that corresponds to CgHMO. Its IR and proton NMR spectra are shown below. In its 13C NMR proton-decoupled spectrum there are 8 lines. " ;-’.Lf!'=:r‘.. ,Ea; Zéaafign agwa l (a) Label 3 characteristic bands in the IR spectrum above. (b) Suggest a structure for compound X (place in the box above). 2000 m 1500 1300 1100 ICC!) 4h, 4. ma_;ihéagés§iga§éé RSEl-ss-g- ' a EEfiEfiEE%E%E§_.--WswVE .. m ‘ fififlfifi%§%§fi§m : fififigfifigflfl%%%figfifiw Efiifigfigfifi‘fiafi%§§ w agggggggggfigfl%fi%%%fiw fi§§§ 900 ul IE; ‘1’: - I‘ :3 '1 - = - 'xiifigfg “fiv§%%%%%aw 20 : i. - - (c) Match each peak in the proton spectrum to that in your structure (label with 'a', 'b', etc.). (d) Of the 8 singlets in the 13C NMR, which peak is furthest downfield? That is, give an approximate chemical shift and indicate to which carbon in 'X' this shift corresponds. ...
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2_21_2001 - NAME: (please PRINT) Chemistry 1303 Exam 2...

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