RT Book, Section
A1 Renslo, Adam
A2 Renslo, Adam
SR Print(0)
ID 1124842336
T1 Stereochemistry
T2 The Organic Chemistry of Medicinal Agents
YR 2016
FD 2016
PB McGraw-Hill Education
PP New York, NY
SN 9780071794213
LK accessbiomedicalscience.mhmedical.com/content.aspx?aid=1124842336
RD 2024/04/20
AB In  this  chapter  we  will  consider  the  stereochemistry  of  organic  molecules,  a  topic  that  is  concerned  with  how  the  atoms  of  a  molecule  are  arranged  in  three  dimensions.  This  is  an  important  topic  in  pharmaceutical  chemistry  because  the  shape  of  a  drug  molecule  affects  both  its  desired  biological  activity  and  its  potential  for  exhibiting  undesired  effects.  To  introduce  the  topic  of  stereochemistry,  consider  the  three  chemical  drawings  shown  below  (Figure  3.1).  Each  of  these  representations  describes  a  six-membered  carbon  ring  with  two  methyl  groups  attached  at  defined  positions—all  three  drawings  describe  the  molecule  1,3-dimethylcyclohexane.  However,  as  one  moves  from  the  first  to  second  drawing,  additional  important  information  is  conveyed.  Whereas  the  first  drawing  tells  us  only  about  the  connectivity  of  carbon  atoms,  the  second  tells  us  about  the  relative  orientation  of  the  two  methyl  groups—one  is  projecting  out  of  the  plane  of  the  paper  whereas  the  other  is  receding  behind  it.  This  drawing  describes  a  specific  stereoisomer  of  1,3-dimethylcyclohexane.  An  even  more  informative  representation  is  provided  in  the  third  drawing,  which  tells  us  not  only  about  the  relative  orientation  of  the  methyl  groups  but  also  about  the  relative  positioning  of  all  the  carbon  atoms  in  the  cyclohexane  ring.  This  third  drawing  attempts  to  illustrate  the  actual  three  dimensional  shape  of  1,3-cyclohexane,  including  its  conformation,  a  topic  we  will  cover  in  detail  in  the  following  chapter.