Synthetic Studies of Daphniphyllum Alkaloids: A New Method for the Construction of [7-5-5] All-carbon Tricyclic Skeleton

Daphniphyllum alkaloids have a complex molecular structure; thus, their synthesis can be challenging. A new method for the construction of the [7-5-5] tricyclic core of Daphniphyllum alkaloids was developed. The bicyclo[5.3.0]decane skeleton was constructed via the divinylcyclopropane rearrangement of a cyclopentenone derivative with a vinylcyclopropyl group at the β-position. After introducing a 2-iodoethyl group via a regioselective Michael addition with phenyl vinyl selenone, the [7-5-5] tricyclic system was formed by the intramolecular alkylation reaction of a cyclopentadienyl anion species.

Chemical Synthesis of Acyclic Nucleoside Phosphonate Analogs Linked with Cyclic Systems between the Phosphonate and the Base Moieties

The syntheses of acyclic nucleoside phosphonate (ANP) analogs linked with cyclic systems are described in the present review. The purpose of the review is to report the methodology of ANP analogs and to give an idea on the synthesis of a therapeutic structural feature of such analogs. The cyclopropane systems were mainly prepared by diazomethane cyclopropanation catalyzed by Pd(OAc)2, intramolecular alkylation, Kulinkovich cyclopropanation, and use of difluorocyclopropane, and so forth. The preparation of methylenecyclopropane system was made by diazoacetate cyclopropanation catalyzed by Rhodium followed by addition-elimination reactions. For the preparation of a variety of tethered 1,2,3-triazole systems, 1,3-dipolar cycloaddition between azidealkylphosphonates and propargylated nucleobases was mainly applied. The formation of various phosphonate moieties was achieved via phosphonylation of alkoxide, cross-coupling between BrZnCF2P (O)(OEt)2 with iodoalkens catalyzed by CuBr, Michaelis-Arbuzov reaction with phosphite, and Rh(II)-catalyzed O-H insertion, and so forth.

Alkylation of 2(3H)-Furanones: Inter- versus Intra-Molecular

In this review, a survey on the behavior of 2(3H)-furanones as alkylating agents is systematized. It is obvious that the direction of the reaction was mainly dependent on the solvent used. Furanones reacted with AlCl3 in excess benzene, toluene, or anisole to give the corresponding butadienecarboxylic acids via an intermolecular alkylation mode. Carrying out the reaction in tetrachloroethane and nitrobenzene as solvents, the reactions may lead to intramolecular alkylation mode or fail to give any product and the unreacted furanones were isolated, depending upon the electron density on C-2 at the aryl group situated at position-3.