10-08 - Select the structure that is a conformer(formed by a ring flip of compound 1 CH3 Br Select the structure that is a conformer(formed by a

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Unformatted text preview: 10/8/2010 Select the structure that is a conformer (formed by a ring flip) of compound 1. CH3 Br Select the structure that is a conformer (formed by a ring flip) of compound 1. 1 Br CH3 Br CH 3 Br CH3 Br CH3 H H 5 CH3 6 3 2 1 4 5 2 6 1 Br 4 H 3 Br CH 3 3 H A B C D H 5 6 1 Br 4 1 32 CH 3 H 2 Select the structure that is a conformer (formed by a ring flip) of compound 1. CH3 Br Br CH 3 So then how are C and D related? CH3 Br Br CH 3 Br CH3 trans-1-bromo-3-methylcyclohexane bromoBr CH3 Br cis-1-bromo-4-methylcyclohexane bromo- CH3 1 C A. Structure D is a conformer of C. D Br CH3 cis-1-bromo-3-methylcyclohexane bromo- ? B. Structure D is the resonance structure of C. C. They are mirror images of one another. D. They are constitutional isomers. E. This makes my head hurt. 3 4 So then how are C and D related? CH3 Br Br CH 3 Br CH3 Is the person you look at in the mirror really you? 1 C Br D Br Br = CH3 H 3C CH3 . . 6 A. Structure D is a conformer of C. B. Structure D is the resonance structure of C. C. They are mirror images of one another. D. They are constitutional isomers. E. This makes my head hurt. 5 1 10/8/2010 Which of the following images are chiral? Which of these compounds is(are) chiral? is(are) chiral? HBr Br H Z 1 A. B. C. D. E. 1 and 5 only 1, 2 and 4 only 1, 3 and 5 only All of them None of them 7 . Br Br H Br H Br 1 2 A. B. C. D. 1 2 Neither Both 2 3 4 5 8 Are these really different compounds? YES! H Br Br H If they are different, how are they related? They are enantiomers of one another. enantiomers H Br Br H Br R-2-bromobutane S-2-bromobutane * Different configurations, NOT different conformations A stereogenic center –where an interchange of two groups produces a stereoisomer. 9 10 There are stereoisomers, configurational isomers and stereoisomers, conformational isomer = How many different kinds of isomers isomers. are there in organic chemistry? What do these isomers have in common and how are they they different? diastereomers = stereoisomers that are not mirror images. C4H8 Stereogenic centers enantiomers diastereomers 11 C4H8 12 2 10/8/2010 What do these isomers have in common and how are they they different? What do these isomers have in common and how are they they different? enantiomers = mirror images that are not identical HO H H OH HO H H OH 2-heptanol is a chiral chiral molecule C7 H16 O Stereogenic centers – more specifically, chirality centers. chirality H OH H OH H OH C7 H16 O 13 14 OH H H OH H OH Do pure enantiomers and pure diastereomers exhibit the same boiling points, melting points and solubilities (in achiral solvents)? OH OH So then why are we making such a fuss about chiral compounds? Do we frequently perceive molecular chirality in our daily lives? (R)-2-heptanol o (S)-2-heptanol o trans trans-2-butene cis-2-butene cis -106 oC O O bp 159 C A. = 159 C Same B. Same C. Different D. Different E. Not enough information on the slide. Same -139 Different Same Different oC H (S)-carvone oil of caraway H (R)-carvone oil of spearmint 15 16 H OH O HO O H Why does one enantiomer usually have a different effect in a biological system? Which of the two binding sites below will our drug have a greater binding affinity for? Our Drug S isomer is the active Ibuprofen enantiomer. enantiomer. 17 A. B. 18 3 10/8/2010 OH O H2N N H S Different enantiomers of a drug can have different effects. oxytocin O H HN O HN S O H N N O H N H2N O N H O O N H O NH2 O O NH 2 H2N H amphetamine H NH2 Hormone best known for its role in female reproduction. Also known as the “cuddle hormone.” stimulant adverse cardiovascular effects 20 19 Different enantiomers of a drug can have different effects. Thalidomide O O How can you spot chirality centers? How many chirality centers are there in ondansetron? ondansetron? Look for carbon atoms that contain 4 different substituents. N NH O O O N NH O O O O * N N N Alleviates morning sickness in pregnant women Caused birth defects ondansetron A. 0 B. 1 C. 2 D. 3 E. more than 3 21 22 Which of these compounds is(are) is(are) chiral? chiral? N N F N OH N N N O H Is the active form of naproxen the R or S isomer? isomer? N N F N OH N N N O F H * naproxen 2 OH O F fluconazole 1 A. B. C. D. 1 2 Neither Both * naproxen 2 OH O A. R B. S fluconazole 1 23 24 4 10/8/2010 How are the R and S designations determined? A. Assign priorities to the substituents about a chirality center. A. 1. Compare atoms directly attached to the chirality center. The larger element wins. 2. If two atoms attached to the chirality center are the same, then compare the next set of atoms. 3. Multiple bonds are counted as either 2 (for double) or 3 (for triple). 3 H atoms H How are the R and S designations determined? A. A. Assign priorities to the substituents about a chirality center. B. With the lowest priority furthest from the viewer, draw a circle from the highest (1) to lowest priority (3). (1) (3) R = clockwise (right) S = counter clockwise (left) * O OH O Hydrogen Hydrogen always gets the lowest priority. But don’t assume all chirality centers have an H. O H OH O A. R B. S 3 O atoms atoms 3 C atoms 25 26 How are the R and S designations determined? A. A. Assign priorities to the substituents about a chirality center. B. With the lowest priority furthest from the viewer, draw a circle from the highest (1) to lowest priority (3). (1) (3) How How are the R and S designations determined? “The “The Hand Method” A. A. Assign priorities to the substituents about a chirality center. B. Point your thumb in the direction that the lowest priority is facing. C. Curl your other fingers. D. If the direction of the curling matches the direction of the top three groups with your right hand, the designation is R (with your left, it’s S). R = clockwise (right) S = counter clockwise (left) H OH O O H HO O O Br H A. (R)-2-bromobutane B. (S)-2-bromobutane 27 28 How are the R and S designations determined? What is the correct name of the following compound? CH 3 H Cl Br A. (R)-1-bromo-1-chloroethane A. bromoB. (S)-1-bromo-1-chloroethane bromo29 5 ...
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This note was uploaded on 12/05/2010 for the course CHE 321 taught by Professor Fowler/sampson during the Fall '08 term at SUNY Stony Brook.

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