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1.
Chemistry ; 25(69): 15929-15933, 2019 Dec 10.
Article in English | MEDLINE | ID: mdl-31584737

ABSTRACT

The synthesis of enantiopure ABCE and ABCD tetracyclic advanced intermediates en route to madangamine alkaloids and studies for the construction of the triunsaturated 15-membered D ring of madangamine B and the saturated 13-membered D ring of madangamine E are reported.

2.
Alkaloids Chem Biol ; 74: 159-99, 2015.
Article in English | MEDLINE | ID: mdl-25845061

ABSTRACT

This chapter is focused on madangamines, a small group of complex diamine alkaloids isolated from marine sponges of the order Haplosclerida, and covers their isolation, characterization, biogenesis, biological activity, and synthesis. Structurally, madangamines are pentacyclic alkaloids with an unprecedented skeletal type, characterized by a common diazatricyclic core and two peripheral macrocyclic rings. The isolation of these alkaloids from Xestospongia ingens (madangamines A-E) and Pachychalina alcaloidifera (madangamine F) is described in detail. Physical and complete spectroscopic 1H and 13C NMR data are included. The proposed biogenesis of madangamines from ammonia, a functionalized three-carbon unit, and saturated or unsaturated linear long-chain dialdehydes, via partially reduced bis-alkylpyridine macrocycles, is discussed. The synthesis of alkaloids of the madangamine group has been little explored, with only one total synthesis reported so far, that of (+)-madangamine D. This review also describes several model synthetic approaches to the diazatricyclic ABC core of these alkaloids, as well as model studies on the construction of the (Z,Z)-unsaturated 11-membered E macrocycle common to madangamines A-E, the 13- and 14-membered D rings of madangamines C-E, and the all-cis-triunsaturated 15-membered D ring of madangamine A. Some members of this group have shown significant in vitro cytotoxicity against a number of cancer cell lines.


Subject(s)
Alkaloids/chemistry , Alkaloids/pharmacology , Porifera/chemistry , Alkaloids/isolation & purification , Alkaloids/metabolism , Animals , Chemistry Techniques, Synthetic , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Xestospongia/chemistry
3.
Angew Chem Int Ed Engl ; 53(24): 6202-5, 2014 Jun 10.
Article in English | MEDLINE | ID: mdl-24798407

ABSTRACT

Madangamines are a group of bioactive marine sponge alkaloids, embodying an unprecedented diazapentacyclic skeletal type. The enantioselective total synthesis of madangamine D has been accomplished, and represents the first total synthesis of an alkaloid of the madangamine group. It involves the stereoselective construction of the diazatricyclic ABC core using a phenylglycinol-derived lactam as the starting enantiomeric scaffold and the subsequent assembly of the peripheral macrocyclic rings. The synthesis provides, for the first time, a pure sample of madangamine D and confirms the absolute configuration of this alkaloid family.


Subject(s)
Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Alkaloids , Heterocyclic Compounds, 4 or More Rings/chemistry , Molecular Structure
4.
Chem Commun (Camb) ; 49(30): 3149-51, 2013 Apr 18.
Article in English | MEDLINE | ID: mdl-23474469

ABSTRACT

The enantioselective synthesis of advanced tetracyclic precursors of madangamine D, bearing rings ABCD of this alkaloid, is reported. The saturated 14-membered ring is assembled from functionalized diazatricyclic intermediates following either ring-closing metathesis or macrolactamization strategies.


Subject(s)
Heterocyclic Compounds, 4 or More Rings/chemistry , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Molecular Structure , Stereoisomerism
5.
Org Lett ; 14(15): 3916-9, 2012 Aug 03.
Article in English | MEDLINE | ID: mdl-22830949

ABSTRACT

Using simplified model derivatives, the assembly of the macrocyclic rings of madangamines, including the 13- and 14-membered D rings of madangamines C-E, the all-cis-triunsaturated 15-membered D ring of madangamine A, and the (Z,Z)-unsaturated 11-membered E ring common to madangamines A-E, has been studied.


Subject(s)
Alkaloids/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Models, Molecular , Alkaloids/chemistry , Cyclization , Heterocyclic Compounds, 4 or More Rings/chemistry , Molecular Structure , Stereoisomerism
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