Categories: Synthesis of N-Heterocycles > Lactams >
Synthesis of γ-lactams
Recent Literature
A highly diastereoselective reaction of 2,5-bis(trimethysilyloxy)furan with
imines gives β-carboxy-γ-lactams and their ethyl ester derivatives in
high yields via a Mukaiyama-aldol type reaction with high diastereomeric ratio
employing Sc(OTf)3 as catalyst.
M. Pohmakotr, N. Yotapan, P. Tuchinda, C. Kuhakarn, V. Reutrakul, J. Org. Chem., 2007,
72, 5016-5019.
The hypervalent iodine reagent PIFA promotes the efficient intramolecular
electrophilic cyclization of easily accessible alkynylamides and alkynyl
carboxylic acids, leading to pyrrolidinone and lactone skeletons, respectively.
A synthetic study and a mechanistic proposal for these transformations are
presented.
I. Tellitu, S. Serna, m. T. Herrero, I. Moreno, E. Domínguez, R. SanMartin, J. Org. Chem., 2007,
72, 1526-1529.
The
utility of a Design of Experiments (DoE) approach for the rapid and
efficient optimisation of a microwave assisted Ugi 3cc reaction of levulinic
acid with a range of amine and isonitrile substrates is demonstrated. The
optimal procedure developed using this approach has enabled the preparation
of lactam derivatives in moderate to excellent yields (17–90%) in a
reaction time of only 30 min compared to the conventional methodology which
required up to 48 h.
H. Tye, M. Whittaker, Org. Biomol. Chem., 2004,
2, 813-815.
The reaction of amide and thioamide dianions with epibromohydrin resulted in
regioselective formation of 5-(hydroxymethyl)pyrrolidin-2-ones (pyroglutaminols)
and -thiones.
I. Freifeld, H. Armbrust, P. Langer, Synthesis, 2006, 1807-1808.
Under selected conditions, the Zr-catalyzed reaction of EtMgCl with imines
produces C,N-dimagnesiated compounds, which can be further trapped with
electrophiles. The overall transformation provides a new route to
bifunctional or cyclic nitrogen-containing compounds such as
1-azaspirocyclic γ-lactams, pyrrolidines and azetidines.
V. Gandon, P. Bertus, J. Szymoniak, Synthesis, 2002, 1115-1120.
Several Pd-catalyzed oxidative cyclizations proceed in excellent yield under
simple aerobic conditions. Importantly, this system provided entry into
enatioselective catalysis with a readily available Pd-sparteine complex.
R. M. Trend, Y. K. Ramtohul, E. M. Ferreira, B. Stoltz,
Angew. Chem. Int. Ed., 2003, 42, 2892-2895.
Catalytic hydrogenation of acetylenic aldehydes using a chirally modified
cationic rhodium catalysts enables highly enantioselective reductive
cyclization to afford cyclic allylic alcohols. Using an achiral
hydrogenation catalyst, some chiral racemic acetylenic aldehydes engage in
highly syn-diastereoselective reductive cyclizations.
J. U. Rhee, M. J. Krische, J. Am. Chem. Soc., 2006, 128, 10674-10675.
N-Alkenyl β-ketoamides undergo a mild cyclization in the presence of
Au[P(t-Bu)2(o-biphenyl)]Cl and AgOTf with excellent regioselectivities and
yields. The reaction provides an efficient method to prepare highly substituted
lactams.
C.-Y. Zhou, C.-M. Che, J. Am. Chem. Soc., 2007,
129, 5828-5829.
Preferential Rh(II) carbenoid intramolecular C-H versus O-H insertion derived
from α-diazo-acetamides can be achieved in water by creating a large hydrophobic environment around the reactive carbenoid center using an
appropriate combination of the catalyst and amide groups.
N. R. Candeias, P. M. P. Gois, C. A. M. Afonso, J. Org. Chem., 2006, 71, 5489-5497.
A new type of C2-symmetric chiral diene ligand was applied
successfully in the Rh-catalyzed asymmetric arylation of N-tosylarylimines
with arylboronic acids to give a broad range of highly enantiomerically enriched
diarylmethylamines as well as 3-aryl substituted phthalimidines.
Z.-Q. Wang, C.-G. Feng, M.-H. Xu, G.-Q. Lin, J. Am. Chem. Soc., 2007,
129, 5336-5337.
A new Pd-catalyzed oxidation reaction for the stereospecific conversion of
enynes into cyclopropyl ketones proceeds with net inversion of geometry with
respect to the starting olefin. This result is consistent with a mechanism in
which the key cyclopropane-forming step involves nucleophilic attack of a
tethered olefin onto the PdIV-C bond.
L. L. Welbes, T. W. Lyons, K. A. Cychosz, M. S. Sanford, J. Am. Chem. Soc., 2007,
129, 5836-5837.
