Winter 2006 blank.pdf

Name:___________________ Page1 (W.06.215.E1.p1) OH OH HOH 3 CO excess H 2 CrO 4 HCl (a) I. (28 points) Complete the following reaction sequences, including stereochemistry as required. If stereoisomers are formed, draw one isomer and write in the box "+ enantiomer" or "+ diastereomer" 4 4 4 (b) J Org Chem 2005, 70 10619 O 1) B 2 H 6 , THF 2) NaOH, H 2 O 2 HOCH 2 CH 2 OH C 18 H 30 O 3 Hint: Two functional group transformations take place Jones: CrO 3 H 2 O/ H 2 SO 4 4 4 8 H 2 SO 4 catalytic TsOH 0 o C C 19 H 25 ClO 4 (CH 3 CH 2 ) 3 N CH 3 I Name:___________________ Page2 (W.06.215.E1.p2) II. (18 points) (a) J. Am. Chem. Soc. 2006 128, 199 C OH H C C C OCH 3 O B - C OH C C Compound A Compound D Compound C Compound A is transformed to Compound C. The transformation is catalyzed by a base, B: - . The mechanism includes the intermediate, Compound D. Draw Compound D and the mechanism illustrating the transformation of D to Compound C. You may use HB and B: - for any Bronsted acid and base that you need to use. Compound X N CH 2 SH O S O O HO (b) 8 3 2 O HO H C O OCH 3 Draw both Compund D and the mechansim for forming Compound C OH (iii) Give the structure of a base that, even in excess, would still only give the monodeprotonation product of Compound X (iv) Give the structure of a base that, even in excess, would still only give the dideprotonation product of Compound X 2 3 CH 3 (i) A base is used to deprotonate Compound X forming its monoanion. Draw the monoanion: ii) An excess amount of a base is mixed with Compound X forming its dianion. Draw the dianion: Name:___________________ Page3 (W.06.215.E1.p3) III. (30 points) Provide a complete, step-wise, balanced mechanism for the following transformation. You may use HB and B - for any Bronsted acid and base that you need to use. (J Org Chem 2006, 71, 420) OCH 3 OCH 3 Si H 3 C OH H 3 C OH Si H 3 C O O acid catalyst OCH 3 OCH 3 Si H 3 C (i) Draw the mechanism through the acetal intermediate shown (ii) Draw the mechanism from the acetal intermediate to the product OCH 3 O Si H 3 C OH Si H 3 C O O 15 15 Name:___________________ Page4 (W.06.215.E1.p4) IV. (23 points) (a) J Org Chem 2006 71, 840 F 3 C CH 3 O CH 3 N CH 3 Show the connectivity of the product Circle the number of stereoisomers formed: 0 1 2 3 4 1) LiAlH 4 2) H 3 O + H Use a word to describe the relationship of the stereoisomers if more than one: (b) 4 5 CH 3 Br Compound Z Compound Z can undergo nucleophilic substitution reactions. The mechanism of this substituion would be: (Circle one) S N 1 S n 2 Using the generic nucleophile Nu, provide all possible products (including stereoisomers) of the substituion reactions: Draw all possible products of an elimination reaction including all stereoisomers If Compund Z were mixed with NaOCH 3 in CH 3 OH the most likely reaction to take place is: (Circle one) Substitution Elimination a mix of both Substitition and Elimination If Compund Z were mixed with CH 3 OH the most likely reaction to take place is: (Circle one) Substitution Elimination a mix of both Substitition and Elimination 1 4 5 2 2 Name:___________________ Page5 (W.06.215.E1.p5) O OH O O O O Br Br NaH O O O O OH O PI 3 NaN 3 V (21 points)Complete the following reaction sequences, including stereochemistry as required. (a) Org Lett 2006 8, 297 (b) J Org Chem 2006 71 420 Br OCH 3 OCH 3 Mg Substitution at Si H 2 O Si H 3 CCl 3 3 3 3 3 3 3 F 3 CS O O OH H 2 O many reactions HCl C 14 H 17 N 3 O 5 Amy2 I