The use of organocopper conjugate addition-enolate trapping for the efficient conversion of thiin-4-one derivatives (8) into dialkylated dihydrothiin-4-ones (9) indicated that a-iodo- sulphones (10) should be readily available. Compounds 10 would be expected to undergo the Ramberg-Bäcklund reaction (Paquette 1977) on treatment with base to produce cyclopentenes 11, which would be the ideal precursors to cyclopent-3-enones (12), which are relatively inaccessible by other methods, and cyclopent-2-enones (13). Model studies showed that this sequence did indeed provide an efficient route to cyclopentenones (scheme 5).
The use of organocopper conjugate addition-enolate trapping for the efficient conversion of thiin-4-one derivatives (8) into dialkylated dihydrothiin-4-ones (9) indicated that a-iodo- sulphones (10) should be readily available. Compounds 10 would be expected to undergo the Ramberg-Bäcklund reaction (Paquette 1977) on treatment with base to produce cyclopentenes 11, which would be the ideal precursors to cyclopent-3-enones (12), which are relatively inaccessible by other methods, and cyclopent-2-enones (13). Model studies showed that this sequence did indeed provide an efficient route to cyclopentenones (scheme 5).
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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I want to summarize this in a simple and clear way
Summarize the written in an understandable style
please quickly.
![R
12
MILD H*
.CO,R
R2
BASE
R2
10
11
13
R'
SCHEME 4. Ramberg-Bäcklund approach to disubstituted cyclopentenones.
The use of organocopper conjugate addition-enolate trapping for the efficient conversion of
thiin-4-one derivatives (8) into dialkylated dihydrothiin-4-ones (9) indicated that a-iodo-
sulphones (10) should be readily available. Compounds 10 would be expected to undergo the
Ramberg-Bäcklund reaction (Paquette 1977) on treatment with base to produce cyclopentenes
11, which would be the ideal precursors to cyclopent-3-enones (12), which are relatively
inaccessible by other methods, and cyclopent-2-enones (13). Model studies showed that this
sequence did indeed provide an efficient route to cyclopentenones (scheme 5).
o co2CH2CH-CH2
Co,CH2CH=CH2
2
S.
14
15
3
17
16
5
19
18
20
Reagents: 1. BuMgBr 2.5% CuBr.SMe, then NaH, CH2-CHCH,Br
2. (Ph,P), Pd - morpholine
3. MCPBA then Me, Sil, ethylene glycol
4. KOBU', THF, -78°C
5. Py.HOTS, Me,cO, H2O
6. 5% HCI - THF
SCHEME 5. Ramberg-Bäcklund model studies.
[ 66 ]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F6abb4e60-07ab-4b34-b98d-0bfcba9ffb10%2F2073d79c-aeab-4c97-a5cf-b781a5e27d52%2Flv1lcim_processed.jpeg&w=3840&q=75)
Transcribed Image Text:R
12
MILD H*
.CO,R
R2
BASE
R2
10
11
13
R'
SCHEME 4. Ramberg-Bäcklund approach to disubstituted cyclopentenones.
The use of organocopper conjugate addition-enolate trapping for the efficient conversion of
thiin-4-one derivatives (8) into dialkylated dihydrothiin-4-ones (9) indicated that a-iodo-
sulphones (10) should be readily available. Compounds 10 would be expected to undergo the
Ramberg-Bäcklund reaction (Paquette 1977) on treatment with base to produce cyclopentenes
11, which would be the ideal precursors to cyclopent-3-enones (12), which are relatively
inaccessible by other methods, and cyclopent-2-enones (13). Model studies showed that this
sequence did indeed provide an efficient route to cyclopentenones (scheme 5).
o co2CH2CH-CH2
Co,CH2CH=CH2
2
S.
14
15
3
17
16
5
19
18
20
Reagents: 1. BuMgBr 2.5% CuBr.SMe, then NaH, CH2-CHCH,Br
2. (Ph,P), Pd - morpholine
3. MCPBA then Me, Sil, ethylene glycol
4. KOBU', THF, -78°C
5. Py.HOTS, Me,cO, H2O
6. 5% HCI - THF
SCHEME 5. Ramberg-Bäcklund model studies.
[ 66 ]
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