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Med Chem > Lecture 3 (Intro to MedChem) > Flashcards

Lecture 3 (Intro to MedChem) Flashcards

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1
Q

Most drugs are less than ____ Da

A

500

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2
Q

conformational freedom

A

the ability to rotate bonds freely

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3
Q

Rotatable bonds are any single bonds that are: ???

A
  • not part of a ring
  • not formed with a terminal atom
  • not formed with a hydrogen atom
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4
Q

are amide C-N bonds freely rotatable?

A

no

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5
Q

bioavailability of ___% is considered the minimum bioavailability for the drug to be used orally

A

20

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6
Q

with decreasing # of rotatable bonds, the bioavailability ______

A

increases

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7
Q

we want delta G to be ___?

A

negative

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8
Q

molecules with lots of freely rotating bonds ____ delta G

A

increases (unfavourable)

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9
Q

What are Lipinski’s Rule of Fives used to determine?

A

If a chemical compound can be absorbed orally

*does not dictate pharmacological activity

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10
Q

What are the Lipinski’s Rule of Fives? (5)

A

1) molecular weight < 500
2) logP < 5
3) < 5 H-bond donors (Sum of NH and OH)
4) < 10 H-bond acceptors (Sum of N and O)
5) < 10 rotatable bonds

Note:
#5 was an additional rule added since Lipinski's original article
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11
Q

Often only one isomer will have biological activity. Why?

A

Because it is the only configuration that will bind to a receptor

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12
Q

In what ways can isomers differ from each other?

A
  • different potency
  • metabolized differently
  • differing toxicity
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13
Q

What are the 3 types of isomers?

A
  • constitutional (structural/positional)
  • configurational
  • conformational
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14
Q

Describe constitutional (structural/positional) isomers

A
  • same atomic composition but
  • different bonding arrangements between atoms

ex. catechol vs. resorcinol

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15
Q

Describe configurational isomers

A

-same molecular formula and the same bonds
but
-atoms are arranged differently in space with respect to each other
(think of chiral compounds ex cis/trans)

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16
Q

Two types of configurational isomers?

A
  • optical

- geometric

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17
Q

Describe optical isomers

A
  • mirror images
  • non-superimposable
  • chiral molecules
  • an asymmetric carbon centre that has 4 different groups/atoms bound to it
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18
Q

optical isomers are ____

A

enantiomers

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19
Q

Define enantiomer

A

non-superimposable mirror images of each other

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20
Q

optical isomers have ___ physical and chemical properties

A

identical

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21
Q

Two important differences in properties between enantiomers ?

A

1) rotation of plane polarized light

2) interaction w chiral environments

22
Q

Describe the rotation of plane polarized light in enantiomers

A

each enantiomer rotates plane polarized light to the same degree but different direction

23
Q

dextrorotary (d) or (+)-enantiomer rotates plane polarized light which way??

A

to the right (clockwise)

24
Q

levorotatory (l) or (-)-enantiomer rotates plane polarized light which way?

A

to the left (counterclockwise)

25
Q

T or F: you can determine direction of rotation by looking at a compound’s structure

A

false man

-need a polarimeter to determine direction of plane polarized light experimentally

26
Q

What type of mixture will not rotate plane polarized light at all?

A

50:50 mixture (racemic mixture)

27
Q

For ‘n’ asymmetric centers there are at most __ configurational isomers

A

2^n

28
Q

What are diastereomers?

A
  • compounds with more than one asymmetric centre
  • not mirror images
  • not superimposable
29
Q

What are meso structures?

A
  • two identical asymmetric centers
  • mirror images
  • superimposable

(these compounds are not chiral)

30
Q

in a Fischer projection how do we orientate amino acid?

A

COO- is up
NH2 is down

(carboxyl group up)
(amino group down)

31
Q

When we have the amino acid orientated in the correct way as a Fischer projection how do we determine D or L?

A

If the alpha hydrogen is left = L

If the alpha hydrogen is right = D

32
Q

proteins are composed of only what type of amino acids?

A

L-amino acids

33
Q

When the H’s in a Fischer projection point in the same direction = ?
(for diastereomers)

A

erythro

34
Q

When the H’s in a Fischer projection point in opposite directions = ?
(for diastereomers)

A

threo

35
Q

Describe geometric isomers

A
  • sp2 hybridized carbon atoms of alkenes and the attached groups lie in the same plane
  • rotation around double bond is restricted
36
Q

When is it possible to have geometric isomers?

A

If each carbon atom in the double and has different substitutions

37
Q

how do we differentiate between geometric isomers?

A

trans/cis

E/Z

38
Q

How do you determine E or Z?

A

cut double bond in half

-determine if the higher priority molecules are on the same or opposite sides

39
Q

Higher priority molecules on the same side

A

Z (cis)

40
Q

Higher priority molecules on opposite sites

A

E (trans)

41
Q

Describe conformational isomers (conformers)

A
  • isomers characterized by different arrangements of atoms that result from rotation about sigma bonds
  • conformers can interconvert between isomeric forms
42
Q

Newman projections:

what conformation has a higher energy form

A

eclipsed

43
Q

Newman projections:

what conformation has a lower energy form

A

staggered

44
Q

bulky groups overlapping = ____ energy

A

highest

45
Q

we would expect that a drug spends most of it’s time in the ___ form

A

anti (staggered)

- this is the lowest energy form

46
Q

6 membered ring takes one or two forms: what are the two forms

A

boat

chair

47
Q

normally there is ______ _______ around sigma bonds

A

free rotation

48
Q

6 membered rings are all ____ bonds

A

sigma

49
Q

chair vs boat:

what is more favoured

A

chair

boat causes steric interactions between hydrogens or other bulky groups which makes boat conformation unfavourable

50
Q

Explain boat to chair or chair to boat flipping: what happens

A

anything that was axial becomes equatorial

anything that was equatorial becomes axial

51
Q

For bulky substituents the conformation that allows the substituents to be in _____ will predominate

A

equatorial

Med Chem (11 decks)

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