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Various terpenylquinones are synthesized by nucleophilic addition or substitution reactions of 1,4-anthracenediones and further transformed into extended polycyclic systems, which mainly keep the 1,4-quinone moiety fused to different nitrogen- heterocyclic rings into the structure.

Exocyclic allenes constitute useful building blocks in organic synthesis and have recently been identified as key intermediates in the synthesis of natural products. Here the first general method for the most straightforward synthesis of exocyclic allenes reported to date is presented. This method is based on the Barbier-type cyclization of propargyl halides catalyzed by titanium; a safe, abundant, and ecofriendly metal. The reaction proceeds under mild conditions compatible with different functional groups and provides good yields of five-, six-, and seven-membered carbocycles and nitrogen-containing heterocycles bearing an exocyclic allene group. Experimental evidence supporting the proposed reaction mechanism is also provided. Moreover, this procedure can be carried out in an enantioselective manner by using chiral titanocene(III) catalysts. The utility of this method has been proved in the synthesis of the natural alkaloid stemoamide.

The new carbodiimide of title is prepared by solid state metathesis reaction of MgF2, BaF2, and Na2(CN2) (fused Cu ampoule, 650 °C, 2 d).

Methyl ethers of podophyllotoxin [1] and its epimers at positions 7 and 8' were obtained through the corresponding chlorinated or brominated derivatives at position 7. Additionally, the corresponding diol methyl ethers were obtained by reducing the lactone with LiAlH4. 7-O-Methylepipicropodophyllotoxin [12], 7-O-methylpicropodophyllotoxin [13], the diol methyl ethers 15-18 and the corresponding diacetates are described here for the first time. Most of the cyclolignans obtained were evaluated for their cytotoxic activity.

A general approach to the synthesis of enantiomerically pure spirocyclic α,β-butenolides is presented where the fundamental framework is rapidly elaborated by acid- or bromonium ion-induced rearrangement of the carbinol derived by addition of 2-lithio-4,5-dihydrofuran to cyclobutanone. Subsequent resolution of the resulting ketones by either sulfoximine or mandelate acetal technology has been applied effectively. The availability of these building blocks makes possible in turn the acquisition of the enantiomers of dihydrofurans typified by 17, 35, and 38 and lactones such as 25 and 31, as well as the targeted title compounds. Complementary reductions of the early intermediates provide the added advantage that the α- and β-stereoisomeric carbinol series can be obtained on demand. These capabilities have been coordinated to allow the crafting of any member of the series in relatively few steps.

The cyclolignan family of natural products includes compounds with important antineoplastic and antiviral properties such as podophyllotoxin and two of their semisynthetic derivatives, etoposide and teniposide. The latter are included in a wide variety of cancer chemotherapy protocols. Due to these biological activities, cyclolignans have been the objective of numerous studies focused to prepare better and safer anticancer drugs. Several cyclolignans related to podophyllotoxin have been prepared and evaluated for their cytotoxic activities on four neoplastic cell lines (P-388, A-549, HT-29 and MEL-28); some of them have antiviral and immunosuppressive activities.

Three series of trisporins have been prepared using a strategy in which a cross-metathesis is the key step. This reaction has proved to be highly regioselective, allowing the combination of α- or β-ionone derivatives having a 1,1-disustituted olefin with trisubstituted alkenes. The stereochemistry of the newly formed olefins has been established by spectroscopic means.

Several new 6-(3-pyrazolylpropyl) derivatives of 1,4-naphthohydroquinone-1,4-diacetate (NHQ-DA) have been prepared by chemical modifications of the Diels-Alder adduct of alpha-myrcene and 1,4-benzoquinone. All these new compounds and precursors have been evaluated in vitro for their cytotoxicity against cultured human cancer cells of MB-231 breast-adeno carcinoma, A-549 lung carcinoma, and HT-29 colon carcinoma. GI(50) values ranged in and below the micromolar concentration level.

Several new prenyl-1,2-naphthohydroquinone derivatives have been prepared by chemical modifications of Diels-Alder products which were obtained from cycloaddition of alpha-myrcene to 1,2-benzoquinone and then evaluated in vitro for their cytotoxic activity against A-549 lung carcinoma, HT-29 colon carcinoma, and MB-231 breast adeno-carcinoma culture cells. Most of them exhibited GI50 values in the microM-concentration level.

Di-p-chlorobenzyl azodicarboxylate (DCAD) is introduced as a novel, stable, solid alternative to DEAD and DIAD for a variety of Mitsunobu couplings. DCAD/Ph(3)P-mediated reactions in CH(2)Cl(2) generate a readily separable hydrazine byproduct. [reaction: see text]