All Info About Chemistry

Synthesis
DOI: 10.1055/s-0029-1216903

Abstract

The C11-C19 fragment of rhizoxin D was synthesized efficiently
and stereoselectively. Stereoselective induction at C13 was achieved
by means of the Crimmins protocol, whereas a substrate-controlled
lithium aldol reaction gave the desired selectivity at the C17 position.
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1217600

Abstract

()-Tamoxifen was synthesized from
a simple olefin (-stilbene) in 5
steps and 40% overall yield (/ = 74:26).
The phenyl substituted group (4-MeNCHCHOCH)
was attached by a bromination-dehydrobromination-Suzuki
reaction sequence. Subsequently, the ethyl group was attached to
the triarylated olefin by a bromination-Negishi reaction
sequence. Both the Suzuki and Negishi cross-coupling processes are
stereospecific, and the stereoselectivity depends only on the bromination-dehydrobromination reactions.
()-Tamoxifen was also obtained from -stilbene in only 3 steps by using
Heck reaction-bromination-Negishi reaction sequence
in 57% overall yield (/ = 65:35).
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1216895

Abstract

We prepared several activated carbon-supported bimetallic Pd-Pt
catalysts (Pd-Pt/C) by using various reducing
reagents, and examined their catalytic activities for the deuteration
of alkyl-substituted aromatic compounds. Multiple deuterations catalyzed by
Pt-Pd/C proceeded in DO at 180 ˚C
under a H atmosphere, and a synergistic effect was observed
in relation to the incorporation of deuterium at sterically hindered
positions on aromatic rings.
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1217601

Abstract

Novel norbornyl-ferrocene hybrids have been synthesized in excellent
yields via Diels-Alder reactions between 1,2,3,4-tetrahalo-5,5-dimethoxycyclopentadiene
and vinyl- or acryloylferrocenes. Halogen reduction of vinylferrocene
adducts followed by catalytic hydrogenation afforded ferrocenyl-norbornane.
Hybrids showed the dependence of the redox potential on the nature
of the substituents on the norbornyl moiety.
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1217605

Abstract

A new and highly efficient methodology for the stereocontrolled
synthesis of aminodeoxyalditols is described through a dimesylation/intramolecular
S2 nucleophilic substitution ring-forming reaction sequence
from glucose, mannose, and galactose derivatives. The degree of
difficulty and rate of the reaction of dimesylates in the cyclization
process is evaluated and shows the trend: galactose > glucose > mannose
derivatives, which has been identified from our experiments and
classical theories.
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1216898

Abstract

A regioselective Tsuji-Trost reaction of sodium 3-allyl-tetronate
with methyl 5-trimethylsilylpenta-2,4-dienyl carbonate was developed.
Carbon-carbon bond formation at the more highly substituted
terminus of the pentadienyl residue was possible by introduction
of an easy to remove SiMe shielding group at the remote end
of the π-system. This carbonate reacted fast enough to
avoid scrambling and formation of symmetric bisallyl tetronic acids.
The 3-allyl-3-penta-2,4-dienyltetronic acid thus obtained is a key
intermediate en route to the natural spirolactone bakkenolide A.
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1216906

Abstract

Reaction of -dichloronitroalkenes
with base leads to the formation of chlorinated nitrile oxides,
probably via a cyclic intermediate. The 1,3-dipoles can be trapped
with alkenes to give dihydroisoxazoles with a chlorinated side chain
in 3-position. This novel synthetic method is fairly general.
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1216902

Abstract

Iodogen is employed as an efficient oxidizing agent for the conversion
of urazoles and bis-urazoles into the corresponding 1,2,4-triazoles
in good to excellent yields under mild heterogeneous conditions
at room temperature.
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1216899

Abstract

Iridium trichloride catalyzes the ring opening of epoxides by
aryl, heterocyclic, or aliphatic amines under mild conditions. The
reactions proceed at room temperature to afford the corresponding β-amino
alcohols in excellent yields. In general, the aminolysis of cyclopentene
oxide is faster than that of cyclohexene oxide in the presence of
iridium trichloride as a catalyst.
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text

Synthesis
DOI: 10.1055/s-0029-1216908

Abstract

The first members of a new family of heterocarbobicyclic nucleoside
analogues have been synthesized from the / mixture of (4-amino-5,6-dihydro-4-cyclopenta[]thiophen-6-yl)methanols
(/. The separation of the and intermediates
during the preparation of the 6-chloropurine derivatives allowed
a separate preparation of the purine heterocarbanucleosides – and -, from
which — and – were obtained by replacement
of the 6-chloro substituent with amino, hydroxy, and cyclopropylamino
groups. Additionally, the 6-phenylpurinyl analogues – and were
prepared from – and – using
Suzuki-Miyaura methodology. In tests of antiviral and cytostatic
activities, compound showed cytostatic
activity against Molt4/C8 human T lymphoblastic leukemia
cells. Antiviral activity was shown by compounds and against Punta­ Toro virus and
Coxackie virus B4 (compound ).
[...]

© Georg Thieme Verlag
Stuttgart ˙ New York

Get connected:
Table of contents  |  Abstract  |  Full text