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PURINES - kap 24. Reaction with electrophiles at N - Protonation. Reaction with electrophiles at N - Alkylation. Selectivity depends on substituents and conditions. N7/N9: - Sterical factors (Large 6-subst) Termodyn. control (reversible react.). Electrophiles - cancer.

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slide1

PURINES - kap 24

Reaction with electrophiles at N - Protonation

slide2

Reaction with electrophiles at N - Alkylation

Selectivity depends on substituents and conditions

slide3

N7/N9: - Sterical factors (Large 6-subst)

Termodyn. control (reversible react.)

Electrophiles - cancer

slide4

Reaction with electrophiles at N - Acylation / Sulfonation

Acylation products generally unstable

Sulfonation - Stable prod., selective N9

Reaction with electrophiles at N - oxidation

slide6

Reaction with electrophiles at C

E-fil Ar subst, generally not working

Reaction with nucleophiles

slide12

Oxy purines

-Oxo forms

Alkylation, acylation etc

slide15

Synthesis of Purines

Carbonyl condensations

Strategy A - Traube synth. etc

slide16

Carbonyl condensations

Strategy B

Cycloadditions

slide17

Bioactive Purines

DNA / RNA bases

Anticancer / antiviral drugs

slide18

Adenosin og adenosinreseptorligander

Sel. A2A antag.

Parkinston /Alsheimer?

AKB PhD-lecture, august 05

Cytokinins - Plant growth hormones

slide19

Natural products

  • Heteromines
  • Isolated from Heterostemma brownii
  • Treatment of tumors in Taiwanese folk medicine

Agelasines from

marine sponges

(Agelas spp)

Asmarines

for marine sponges

Agelasine D

slide20

Reversine

http://www.scripps.edu/news/press/122203.html

slide21

Heterocycles cont. more than 2 heteroatoms in one ring

kap 26

5-membered rings

Triazoles and tetrazoles

6-membered rings

Triazines and tetrazines

slide22

5-membered rings

Triazoles and tetrazoles (pentazoles highly unstable)

More acidic - less basic comp to diazoles

Bioisostere - CO2H

slide23

1,2,3-Triazole

React. at N

slide24

React. at C

1,2,3-Triazole

slide26

React. at N

1,2,4-Triazole

React. at C

slide28

Small diff. stab. taut.

Tetrazole

Bioisostere - CO2H

React. at N

slide30

Oxadiazoles and thiadiazoles

(thiatriazole)

- No acidic NH

-Generally low basicity

(cf triazoles)

-Some examles N-quart.

-Few ex. Introd of E-fils on C

-Prone to Nu attack

Aromaticity (NMR shifts, bond lenghts)

slide31

Ring opening (esp. O-cont. rings)

C-lithiation easy, but often low stab of lithiated prod

slide32

6-membered rings

Triazines and tetrazines

Highly activated for Nu attack

No simple react with electrophiles

slide33

Diels Alder react. Leading to azines with fewer N

(see synth of pyridines, diazines)