Here we present the preparation of a variety of diarylmethanes obtained via ultrasound Stille coupling under palladium catalysis between some substituted aryl compounds and benzyltributyltin ...compounds generated through sonicated Barbier reaction in a very short time reaction and excellent yield. The study reported below compares different methods to optimize the synthesis of usually unstable benzyltin derivatives and is another contribution to the investigation of Csp3–Csp2 coupling process involving benzyl–aryl reagents. Substituted carboxylated benzophenones were easily prepared in a very good yield by oxidation of some diarylmethanes.
Background:
Organotin(IV) derivatives have appeared recently as potential biologically active metallopharmaceuticals exhibiting a variety of therapeutic activities. Hence, it is important to study ...the synthesis of new organotin compounds with low toxicity that may be of pharmacological interest.
Objectives:
This study focuses on the synthesis of new bis-stannylated derivatives with
C2
symmetry that could be tested as antifungal agents against two clinical important fungal species,
Cryptococcus neoformans
and
Candida albicans.
Methods:
The radical addition of triorganotin hydrides (R
3
SnH) and diorganotin chlorohydrides (R
2
ClSnH) to bis-α,β-unsaturated diesters derived from (S)-BINOL led to the corresponding new bis-stannylated derivatives with
C2
symmetry. Nine pure organotin compounds were synthesized with defined stereochemistry. Four of them were enantiomerically pure and four were diastereoisomeric mixtures.
Results:
All new organotin compounds were fully characterized, those with phenyl ligands bonded to tin were the most active compounds against both the strains (
Cryptococcus neoformans
and
Candida albicans)
, with activity parameters of IC
50
close to those of the reference drug (amphotericin B).
Conclusion:
Nine pure organotin compounds with C2 symmetry were synthesized with defined stereochemistry and their antifungal properties were tested against two clinical important fungi with IC values close to those of the reference drug. The structure-containing preferably two or three phenyl groups joined to the tin atom were highly active against both the strains compared with those possessing tri-
n
-butyl groups.
A systematic study for esterification procedures to the synthesis of BINOL diesters is described. Reaction conditions with trifluoracetic acid anhydride (TFAA) and 85% H
3
PO
4
were selected as the ...best procedure to prepare enantiomerically pure (S)-1,1′-bi-2-naphthol (BINOL) diesters VIII to XI with almost quantitative yields and very short reaction times.
Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications
®
for the following free supplemental resources: Full experimental and spectral details.
Display omitted
An efficient, green, and atom economic methodology for the stereoselective synthesis of C2 symmetry (3R,4R)-TTFOL diester derivatives has been developed. The procedure occurs through ...a (2R,3R)-TADDOL dioxolane cleavage and rearrangement under mild conditions by its reaction with a carboxylic acid in the presence of TFAA/H3PO4 without the need for an inert atmosphere to give generally high yields.
Hydrostannation of mono- and disubstituted alkynes with trineophyltin hydride (
1) leads to vinylstannanes in good to excellent yields, the configuration of the products depending on the reaction ...conditions. Thus, whereas hydrostannation under radical conditions leads stereoselectively to only one of the two possible products corresponding to an
anti addition in 60–99% yield, the additions catalyzed by bis(triphenylphosphine)palladium dichloride gave mixtures of the
syn adducts (60–79% yield). Full
1H-,
13C-, and
119Sn-NMR as well as mass spectra data of the organotin adducts are given.
Radical hydrostannation of mono- and disubstituted alkynes with trineophyltin hydride (
1) under radical conditions leads stereoselectively to only one of the two possible products corresponding to an
anti addition in 60–99% yield. The additions of
1 to the same alkynes catalyzed by bis(triphenylphosphine)palladium dichloride gave mixtures of the
syn adducts (60–79% yield).
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