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Letters in Organic Chemistry
ISSN: 1570-1786
Letters in Organic Chemistry
Volume 4, Number 6, September 2007
Microwave and Polymer Assisted Synthesis of a Small
Library of α,β-
Unsaturated Methyl Esters via the Wittig Reaction
Pp. 384-387
S. Collina, D. Rossi, M. Urbano, A. Carnevale Baraglia and
O. Azzolina
[Abstract]
Chiral N-Allylpyrroles as Versatile Substrates Under
Rhodium Catalyzed Hydroformylation: Good Regio- and Diastereo
Selectivity at Room Temperature and High Pressure
Pp. 388-392
Roberta Settambolo, Silvia Rocchiccioli, Gloria Uccello-Barretta
and Raffaello Lazzaroni
[Abstract]
Synthesis of Ethyl 4-O-[4-(1,2,4-Oxadiazol-5-yl)phenyl]-α-
D mannopy- ranosides Pp. 393-397
Janaína Versiani dos Anjos, Denis Sinou, Sebastião
José de Melo and Rajendra Mohan Srivastava
[Abstract]
Asymmetric Allylation of Aldehydes and Ketones Using
Chiral Pyridine Bis(diphenyloxazoline)-Indium Complexes
Pp. 398-403
Wei-Yi Chen and Xin-Sheng Li
[Abstract]
Tweezers-Type Anion Receptors Based on Diphenoxymethane
and Biphenol Bearing Urea groups Pp. 404-408
Shintaro Higuchi and Kazuaki Ito
[Abstract]
Investigation of the Acid-Catalyzed Rearrangement
of Morphinans Pp. 409-413
Csaba Csutorás, Sándor Berényi and
John L. Neumeyer
[Abstract]
Design, Synthesis and Antitumor Activity of Dimeric
Bile Acid Amino Acid Conjugates Pp. 414-418
Yan Li, Zhen Zhang, Yong Ju and Chang-Qi Zhao
[Abstract]
A Regioselective and Stereoselective Methoxy-Bromination
of Olefins Using (Diacetoxyiodo)benzene and Lithium Bromide
Pp. 419-422
Nandkishor N. Karade, Sumit V. Gampawar and Girdharilal
B. Tiwari
[Abstract]
Synthesis of Chiral 2-(6,8-dichloro-4-methyl-1,1,3-trioxo-3,4
dihydro-1H- 1λ6-benzo[1,2,4]thiadiazin-2-yl)
Carboxylic Acids Derived from Enantiomeric Amino Acids
Pp. 423-428
Imtiyaz Ahmed Khazi and Young-Sik Jung
[Abstract]
Regioselective Reaction between Maltol and Vinyltriphenylphosphonium
Salts: An Efficient One-Pot Synthesis of a Novel Class of
Dihydrofuran and Cyclobutene Derivatives Pp. 429-432
Robabeh Baharfar, Sakineh Asghari, Azam Hamedaninejad,
Atieh Abbasi, Azita Ostadzadeh and Hamid Reza Bijanzadeh
[Abstract]
Preparation of Orthogonally-Protected 3-Methoxy-4
Phosphonomethyl-L- Phenylalanine, a New Reagent for the Synthesis
of Phosphotyrosyl Mimetic-Containing Peptides Pp.
433-439
W.J. Choi, S.-U. Kang and T.R. Burke Jr.
[Abstract]
Mild and Efficient Method for the Synthesis of Flavones
by InCl3 Mediated Cyclization
of 1,3-Diketones: Concise Total Synthesis of Lanceolatin B
Pp. 440-444
Yong Rok Lee and Keon Yong Kang
[Abstract]
An Expeditious “Green” Michael Addition
of Nitro Methane to Benzimidazole Chalcones in the Presence
of TBAB as Surface Catalyst Pp. 445-447
P.K. Dubey, P.V.V. Prasada Reddy and K. Srinivas
[Abstract]
Specificity in Crystal Engineering: Polymerization
and Dimerisation Motif Design in Pyridine System
Pp. 448-451
Shyamaprosad Goswami and Swapan Dey
[Abstract]
Facile Biphasic Deprotection of Aldehyde Dimethylhydrazones
with Aqueous Hydrochloric Acid Pp. 452-455
Richard J. Petroski
[Abstract]
Abstracts
[Back to top]
Microwave and Polymer Assisted Synthesis
of a Small Library of α,β-
Unsaturated Methyl Esters via the Wittig Reaction
S. Collina, D. Rossi, M. Urbano, A. Carnevale Baraglia and
O. Azzolina
An efficient protocol based on the combination of microwave
dielectric heating and PASP synthesis using the Wittig reaction
was developed and applied to the preparation of α,β-unsaturated
methyl esters, key intermediates of new sigma ligands. The
stereochemistry of the products was also investigated showing
a high E:Z isomeric ratio.
[Back to top]
Chiral N-Allylpyrroles as Versatile Substrates Under
Rhodium Catalyzed Hydroformylation: Good Regio- and Diastereo
Selectivity at Room Temperature and High Pressure
Roberta Settambolo, Silvia Rocchiccioli, Gloria Uccello-Barretta
and Raffaello Lazzaroni
The chiral (S)-3-alkyl-3-(pyrrol-1-yl)prop-1-enes 1a-c
were hydroformylated at 20°C and high pressure (100 atm)
giving the branched aldehydes 2-methyl-3-(pyrrol-1-yl)alkanales
(2+2') with a good regio-selectivity and
a high diastereomeric excess (2/2' up to
90:10). The absolute configuration of the diastereomers was
assigned via NMR measurements, 2S,3S being the predominant
one.
[Back to top]
Synthesis of Ethyl 4-O-[4-(1,2,4-Oxadiazol-5-yl)phenyl]-α-
D mannopy- ranosides
Janaína Versiani dos Anjos, Denis Sinou, Sebastião
José de Melo and Rajendra Mohan Srivastava
The palladium-catalyzed reaction of 5-(4-hydroxyphenyl)-1,2,4-oxadiazoles
with ethyl α-O-Δ
3-glucopy-ranoside afforded
ethyl 4-O-[4-(1,2,4-oxadiazol-5-yl)phenyl]-2,3-dideoxy-α-D-erythro-hex-2-enopyranosides.
Bishydroxylation of the latter compounds gave the corresponding
ethyl 4-O-[4-(1,2,4-oxadiazol-5-yl)phenyl]-α-D-mannopyranosides.
[Back to top]
Asymmetric Allylation of Aldehydes and Ketones Using
Chiral Pyridine Bis(diphenyloxazoline)-Indium Complexes
Wei-Yi Chen and Xin-Sheng Li
Indium complexes of chiral pyridine bis(diphenyloxazoline)-type
ligands have been investigated as catalysts for the asymmetric
allylation of aldehydes and ketones. Promoted by these chiral
catalysts, allyltributylstannane reacted with aldehydes and
ketones to afford the corresponding optically active homoallylic
alcohols smoothly.
[Back to top]
Tweezers-Type Anion Receptors Based on Diphenoxymethane
and Biphenol Bearing Urea groups
Shintaro Higuchi and Kazuaki Ito
Diphenoxymethane (1a and 1b)
and biphenol derivatives (1c and 1d)
bearing urea groups were prepared to be used in anion recognition.
Diphenoxymethane derivative (1a) selectively
bound chloride anion (Cl-) in 1:1 complexes. However, biphenol
derivatives (1c and 1d)
did not show a clear selectivity in anion recognition. The
association constants of the complexes were determined by
1H-NMR titrations in CDCl3.
[Back to top]
Investigation of the Acid-Catalyzed Rearrangement
of Morphinans
Csaba Csutorás, Sándor Berényi and
John L. Neumeyer
The acid-catalyzed rearrangement of morphine (1),
codeine (3), 3-deoxynormorphine (14)
and N-cyclopropylmethyl-3-deoxynormorphine (11)
was investigated with methanesulfonic acid. The yield in the
rearrangement reaction was significantly improved using milder
reaction conditions, compared to the earlier reported methods.
As an evidence for the mechanism of the acid-catalyzed rearrangement
of morphinans, the diene intermediate 13
was isolated. A new method, using boron trifluoride etherate
was elaborated for the rearrangement of morphinandienes.
[Back to top]
Design, Synthesis and Antitumor Activity of Dimeric
Bile Acid Amino Acid Conjugates
Yan Li, Zhen Zhang, Yong Ju and Chang-Qi Zhao
Nine dimeric bile acid-amino acid conjugates as the mimic
of cycle peptide and they have been synthesized in good yield
and their structures were well confirmed by 1H
NMR, 13C NMR and mass spectra.
The ESI-MSn technique was
used to probe the conformation of these molecules. The preliminary
bioactivity tests showed that some of the title compounds
could inhibit the growth of human breast cancer cell MCF-7.
The antitumor activity probably derived from the unique sandwich-type
amphiphilic conformation.
[Back to top]
A Regioselective and Stereoselective Methoxy-Bromination
of Olefins Using (Diacetoxyiodo)benzene and Lithium Bromide
Nandkishor N. Karade, Sumit V. Gampawar and Girdharilal
B. Tiwari
A facile regio and stereoselective methoxy-bromination of
alkenes using LiBr and (diacetoxyiodo)benzene as oxidant is
reported.
[Back to top]
Synthesis of Chiral 2-(6,8-dichloro-4-methyl-1,1,3-trioxo-3,4
dihydro-1H- 1λ6-benzo[1,2,4]thiadiazin-2-yl)
Carboxylic Acids Derived from Enantiomeric Amino Acids
Imtiyaz Ahmed Khazi and Young-Sik Jung
A series of new chiral 2-(6,8-dichloro-4-methyl-1,1,3-trioxo-3,4-dihydro-1H-1λ6-benzo[1,2,4]thiadiazin-2-yl)
carboxylic acids 7a-g containing the chiral
amino acid residue were synthesized by adopting the chemical
transformations, which have not affected the chirality of
the amino acid residue. No significant racemization of the
chiral centre was observed during the synthesis of enantiomeric
benzothiadiazine 1,1-dioxide derivatives from the corresponding
D and L amino acids. Structures of all the newly synthesized
compounds were determined by analytical and spectral data.
[Back to top]
Regioselective Reaction between Maltol and Vinyltriphenylphosphonium
Salts: An Efficient One-Pot Synthesis of a Novel Class of
Dihydrofuran and Cyclobutene Derivatives
Robabeh Baharfar, Sakineh Asghari, Azam Hamedaninejad,
Atieh Abbasi, Azita Ostadzadeh and Hamid Reza Bijanzadeh
The reaction of 2-methyl-3-hydroxy-4H-pyrane-4-one (maltol)
with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine
in CH2Cl2
at room temperature leads to the unknown fused furan and cyclobutene
derivatives, and functionalized olefins in fairly high yields.
[Back to top]
Preparation of Orthogonally-Protected 3-Methoxy-4
Phosphonomethyl-L- Phenylalanine, a New Reagent for the Synthesis
of Phosphotyrosyl Mimetic-Containing Peptides
W.J. Choi, S.-U. Kang and T.R. Burke Jr.
[(4-Hydroxymethyl-2-methoxyphenyl)methyl]phosphonic acid di-tert-butyl
ester (8) served as a key intermediate in
the stereoselective preparation of N-Fmoc-3-methoxy-4-(di-tert-butyl)phosphonomethyl-L-phenylalanine
(5). Reagent 5 may be useful
for the solid-phase synthesis of phosphotyrosyl mimetic-containing
peptides.
[Back to top]
Mild and Efficient Method for the Synthesis of Flavones
by InCl3 Mediated Cyclization
of 1,3-Diketones: Concise Total Synthesis of Lanceolatin B
Yong Rok Lee and Keon Yong Kang
A mild and efficient synthesis of flavones was achieved by
indium(III) chloride-mediated reactions of 1,3-diketones in
good yields. As an application of this methodology, total
synthesis of biologically interesting lanceolatin B was carried
out.
[Back to top]
An Expeditious “Green” Michael Addition
of Nitro Methane to Benzimidazole Chalcones in the Presence
of TBAB as Surface Catalyst
P.K. Dubey, P.V.V. Prasada Reddy and K. Srinivas
A novel Michael addition of nitromethane to β-carbon
of the benzimidazole chalcones 1 in the presence
of K2CO3
and TBAB, under solvent-free conditions, by a simple physical
mixing of compounds, leading to 1-(1-alkyl-1H-benzimidazol-2-yl)-4-nitro-3-aryl-butane-1-one
2 is described.
[Back to top]
Specificity in Crystal Engineering: Polymerization
and Dimerisation Motif Design in Pyridine System
Shyamaprosad Goswami and Swapan Dey
2-Amino-6-hydroxymethylpyridine (1) and 2-pivaloylamino-6-hydroxymethylpyridine
(2) are important hydrogen bonding synthons
as they are the very useful substrates which can be used for
the synthesis of designed receptors in the field of molecular
recognition [1] and supramolecular chemistry [2]. Here we
report the compounds 1 and 2
as simple designers to create polymeric supramolecular three-dimensional
assembly and self-complementary dimer respectively in solid-state
crystal engineering.
[Back to top]
Facile Biphasic Deprotection of Aldehyde Dimethylhydrazones
with Aqueous Hydrochloric Acid
Richard J. Petroski
Deprotection of aldehyde dimethylhydrazones was accomplished
by stirring a biphasic mixture of the aldehyde dimethylhydrazone,
1M hydrochloric acid, and petroleum ether at room temperature
for three to seven hours. The method works with α,β-unsaturated-
and diene-aldehyde dimethylhydrazones, which are often difficult
compounds to deprotect. Isolated yields ranged from 85% to
97%. |
