Scalable synthesis of highly reactive 1,3-diamino dienes from vinamidinium salts and their use in Diels-Alder reactions

Article abstract of DOI:10.1021/jo202655h

A practical and chromatography-free synthesis of vinamidinium salts and their use as diene precursors in Diels-Alder reactions is reported. Additionally, 1,3-dipyrrolidino-1,3-butadiene was shown to be significantly more reactive than Rawal's diene in a c

Full text of DOI:10.1021/jo202655h

Scalable Synthesis of Highly Reactive 1,3-Diaminodienes from
Vinamidinium Salts and Their Use in Diels-Alder Reactions
Sida Zhou, Eduardo Sánchez-Larios, and Michel Gravel*
michel.gravel@usask.ca
Department of Chemistry, University of Saskatchewan
110 Science Place, Saskatoon, SK, S7N 5C9, Canada
Supporting Information
Table of Contents
Copies of NMR Spectra ..................................................................................................................................................... 2
(3E)‐4‐morpholinyl‐3‐buten‐2‐one (11a) .......................................................................................................... 2
(Z)‐1‐(3‐methoxybut‐2‐enylidene)morpholinium tetrafluoroborate (12a)........................................ 3
(Z)‐1‐(3‐methoxybut‐2‐enylidene)piperidinium tetrafluoroborate (12b)........................................... 4
(Z)‐1‐(3‐methoxybut‐2‐enylidene)pyrrolidinium tetrafluoroborate (12c) ......................................... 5
(Z)‐1‐(3‐(morpholinyl)but‐2‐enylidene)morpholinium tetrafluoroborate (4a)................................ 6
(Z)‐1‐(3‐(piperidinyl)but‐2‐enylidene)piperidinium tetrafluoroborate (4b)..................................... 7
(Z)‐1‐(3‐(pyrrolidinyl)but‐2‐enylidene)pyrrolidinium tetrafluoroborate (4c).................................. 8
4‐(pyrrolidin‐1‐yl)cyclohexa‐1,3‐dienecarbaldehyde (21)......................................................................... 9
Methyl 1‐methyl‐4‐oxocyclohex‐2‐enecarboxylate (22)............................................................................10
Methyl 6‐phenyl‐4‐(pyrrolidin‐1‐yl)cyclohexa‐1,3‐dienecarboxylate (23)........................................11
N,N‐diethyl‐4‐(phenylamino)‐5‐(pyrrolidin‐1‐yl)biphenyl‐2‐carboxamide (27)............................12
Competition Experiment Between Rawal’s Diene (28) and Diaminodiene 5c..................................13
S1

Copies of NMR Spectra
(3E)-4-morpholinyl-3-buten-2-one (11a)
S2

(Z)-1-(3-methoxybut-2-enylidene)morpholinium tetrafluoroborate (12a)
S3

(Z)-1-(3-methoxybut-2-enylidene)piperidinium tetrafluoroborate (12b)
O
BF4
N
S4

(Z)-1-(3-methoxybut-2-enylidene)pyrrolidinium tetrafluoroborate (12c)
O
BF4
N
S5

(Z)-1-(3-(morpholinyl)but-2-enylidene)morpholinium tetrafluoroborate (4a)
O
N
BF4
N
O
S6

(Z)-1-(3-(piperidinyl)but-2-enylidene)piperidinium tetrafluoroborate (4b)
N
BF4
N
S7

(Z)-1-(3-(pyrrolidinyl)but-2-enylidene)pyrrolidinium tetrafluoroborate (4c)
N
BF4
N
S8

4-(pyrrolidin-1-yl)cyclohexa-1,3-dienecarbaldehyde (21)
S9

Methyl 1-methyl-4-oxocyclohex-2-enecarboxylate (22)
O
OMe
O
S10

Methyl 6-phenyl-4-(pyrrolidin-1-yl)cyclohexa-1,3-dienecarboxylate (23)
S11

N,N-diethyl-4-(phenylamino)-5-(pyrrolidin-1-yl)biphenyl-2-carboxamide (27)
N
H
N
Ph
Ph
O
N
S12

Competition Experiment Between Rawal’s Diene (28) and Diaminodiene 5c
O
H1
H3
CH3
H3
H2
H1
H2
H2
N
H1
H2
H1
TBSO
H1
N
O
H2
H2
H1
H1
H2
TBSO
13c
Competition experiment
N
O
H1
H1
H2
H1
N
S13