Guanidines natural derivatives, from

The Wittig-type reactions of iminophosphoranes with isocyanates and related compounds have also been extensively used in heterocyclic synthesis. Examples include the preparations of the mesoionic [l,3,4]thiadiazolo[2,3-c][l,2,4]triazines (210) from (209), 0 bicyclic guanidines, e.g. (212), from (211), naphthypyridines (215), (216), and (217) from (213) and (214), 2 pyrido[l,2-f]pyrimido-[4,5-d)pyrimidines (218), 7H-pyrido-[4,3-c]- (219) and 10H-pyrido[3,4-b]- (220) carbazoles, tricyclic fused 2,4-diimino-l,3-diazetidines (222) from the bisiminophosphorane (221), benzotriazepines (225) from (223) and (224), 6 and mesoionic thiazolo-[2,3-b]-1,3,4-thiadiazoles (227) and N,N-bisheteroarylamines from the iminophosphorane (226), derived from 3-amino-4-phenylthiazole-2(3H)-thione. The carbodiimides (229), prepared from the iminophosphorane (228), can be converted into quinolines or a-carboline derivatives depending on the nature of the isocyanate used in the reaction with (228) and the reactions of iminophosphoranes (230) and (231) with aryl and styryl isocyanates provide one-pot syntheses of quinoline, a-carboline, and quinindoline derivatives. 9... 

The excellent reviews of Berlinck [1-5] have surveyed a great number of guanidine-type natural products. In addition, some guanidine-derived marine alkaloids have been reviewed by Kobayashi and Ishibashi [6,7]. Also, a recent book gave accounts of marine alkaloids including the phakellins, palau amines and oroidin-like dimers derived from bromopyrroles and polyketide-derived polycyclic guanidine alkaloids [8]. 

Guanidine derivatives of pyrrole series from marine natural products 81MI14. 

Fluorinated biologically active pyrimidines and purines 80YGK1119. Guanidine derivatives of purine from marine natural products 81Mn4. Orotic acid, physiological activity of 85PHA377. 

C5H 4N4, Mr 130.19, mp. 101.5-103 °C. A. is a guanidine derivative formed by decarboxylation of L- ar-ginine. It is an intermediate in the, in plants especially widely distributed, biosynthesis of putrescine from arginine. Natural sources include ergot, the Asteraceae Ambrosia artemisifolia, the sea anemone Anthopleura japonica and herring semen. 

Additionally, the use of Rh2(esp)2 has extended the intramolecular C(sp )—H amination reaction to other types of nitrene precursors (Scheme 11). Appfication of the reaction conditions to ureas and guanidines, thus, gives access to valuable building blocks for the synthesis of drug candidates or natural products.A diverse range of 1,3- and 1,2-diamines is, also, easily accessible, respectively from sulfamides and hydroxylamine-derived sulfamates.In each case, 1—2 mol% of catalyst 3 is sufficient to isolate the expected cycfic products with excellent yields of up to 99%. 

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