LEC TWO ESTABLISHING ORGANIC STRUCTURES DATA LIMITATIONS

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LEC TWOESTABLISHING ORGANIC STRUCTURES DATA
LIMITATIONS
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USES OF MOLECULAR FORMULAOR PARTIAL FORMULA
Unsaturation Number (UN) Hydrogen Deficiency
Index (HDI)
CnH2n2 ref. point ADD H FOR EACH X ADD CH FOR
EACH N OR P OR H FOR EACH N OR P
EXAMPLES UN 1 C6H12O EVEN H COUNT
C6H12 C6H11Cl ODD H COUNT Cl---H
C6H12 C6H13N ODD H COUNT N---CH
C7H14 C6H14N2 EVEN H COUNT N2---C2H2 C8H16
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What is the Unsaturation Number?
C16H18N4Br2Cl2SO2
N4 --- C4H4 Br2 --- H2 Cl2--- H2 S O2
C20H26 42-26/2 8
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FOR THE IMMEDIATE FUTURE
HOW MANY STRUCTURES FIT C2H3O2Cl ?
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(2a2) (b-de)
BEGIN HERE
UN
2
(42)-3-1
C2H3O2Cl
1
2
CaHbOcNdXe
P 8
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NOW THE QUESTION
HOW MANY STRUCTURES FIT C2H3O2Cl
CLASS VOTE HERE TA VOTE HERE
7 STABLE 4 OR MORE UNSTABLE
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C2H3O2Cl 7 STABLE 4 UNSTABLE STRUCTURES
BEGIN HERE
FCN GPS CC OR CO OR RING C-O-Z C-Cl
P 8
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C2H3O2Cl
ACYCLIC
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C2H3O2Cl
CYCLIC
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C2H3O2Cl
SUMMARY
H
Cl
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BEGIN HERE
P 8
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-N-CH3
see pg 12
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A. CASE WHERE LIST OF SUB STRUCTURES IS CLEAR
LE2
LE2
LE3
LE1
?
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B. CASE WHERE LIST OF SUB STRUCTURES NOT CLEAR
P13
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ESTIMATING RINGS
HOW MANY RINGS
HOW MANY RINGS VOTE
2 ________ 3 ________ 4 ________ 5 ________
6 ________
TA VOTE ?
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ESTIMATING RINGS
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Hans-Knöll-Institute for Natural Products
Research, Jena, Germany
Hexacyclinol, a new antiproliferative metabolite
of Panus rudis HKI 0254.Udo Gräfe et.
al. Journal of Antiobiotics 2002, 55, 814-817.
Source Panus rudis HKI 0254 from dead betula
woods near Irkutsk in Siberia Grown in 15L of
broth 21 days at 23 oC. Broth extracted with
EtOAc followed by chromatography! Structure
Elucidation MS, NMR1D and 2D (DEPT, COSY, HMQC,
HMBC, NOESY), IR MF C23H28O7, HRMS m/z
416.1867 (6, calcd. 416.1835) ? 10 degrees of
unsaturation
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• How can compounds with structural skeletons as
  different as those synthesized by La Clair and
  Porco have such similar 1H NMR spectra?

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• The controversy has been hashed over online in
  several chemistry blogs, where La Clair has taken
  a thrashing. In particular, critics have
  chastised him for not including the names of five
  technicians who assisted him as coauthors on the
  paper.

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• "Occasionally, blatantly wrong science is
  published, and to the credit of synthetic
  chemistry, the corrections usually come quickly
  and cleanly," comments Harvard University
  chemistry professor E. J. Corey.

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WHEN IS A STRUCTURE COMPLETE?
BEGIN HERE
P 8
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SUMMARY

• We found structures for C2H3O2Cl 7 stable,
  4 or more unstable!
• 2. Drawing and Manipulating Working Structures is
  important.
• 3. Determining the count of rings for polycyclics
  can be a challenge.
• 4. Choosing between working structures can result
  in errors.
• 5. When is a structure complete?

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Homework for Chapter 1
OSA P18-P22 Problems 1.2, 1.3, 1.6, 1.7, 1.9,
1.10, 1.11, 1.13, 1.14, 1.15, 1.16, 1.17, 1.19,
1.21, 1.22 Next Class (1/16, Wed)