Syntheses of salvilenone and related compounds: II. A novel rearrangement of a tetrahydrophenalenone to a naphthopyranone

The reaction of isopropenyl carbinol ( 2 ) with aqueous hydrobromic acid and hydroiodie acid gave salvilenone ( 1 ) and naphthopyranone ( 3 ) respectively. The reaction mechanism has been investigated. The formation of ( 3 ) was undergone a novel rearrangement of a tetrahydrophenalenone to a naphthopyranone.     

Syntheses of vinca alkaloids and related compounds. 104. A concise synthesis of (-)-vincapusine

beta-Iodo-enamines with an eburnane skeleton (5a and 5c) were obtained with the aid of iodine from compounds 2a and 2c and were then transformed into hydroxyl lactams (6a and 6c) with CuSO4.5H2O in a mixture of DMF and water. Lactams (6a and 6c) were reduced selectively with BH3.SMe2 to result in the first synthesis of (-)-vincapusine (4a) as well as its natural 14-decarbomethoxy analogue (4c).     

Enantioselective total synthesis of marine alkaloids,manzamine A and related compounds

A review of our studies toward the enantioselective total synthesis of ircinal A, manzamine A and related compounds is presented in detail.     

A novel synthesis of benzofuran and related compounds. I. The vilsmeier reaction of phenoxyacetonitriles

A novel synthesis of 2-benzofurancarboxylic acid derivatives by the Vilsmeier reaction of phenoxyacetonitriles is described.     

A simple synthesis of tropones and related compounds

Cyclohexa-2,4- and 2,5-dienones bearing at position 2 or 4 α dihalomethyl group (halogen = chlorine or bromine) are smoothly reduced by tri-butyltin hydride to furnish appropriately substituted tropones. Modification of the substituents permits access to a tropolone and to less substituted tropones. The mechanism of this ring expansion process has been discussed.     

Norrisolide: total synthesis and related studies

A stereoselective synthesis of (+)-norrisolide is presented. This natural product belongs to a family of marine spongiane diterpenes the structure of which is characterized by a fused gamma-lactone-gamma-lactol ring system attached to a bicyclic hydrophobic core. Our studies led to the development of a expedient synthesis of such gamma-lactone-gamma-lactol motifs based on ring expansion of a fused cyclopropyl ester. Highlights of the synthetic strategy toward norrisolide include the coupling of the two bicyclic systems by constructing a sterically demanding C9-C10 bond and the installation of the C19 oxygen at the last step of the synthesis via a Baeyer-Villiger oxidation.     

Silver(I) fluoride and related compounds in chemical synthesis

Silver(I) fluoride is a versatile tool in desulfuration‐fluorination reactions with thiuram disulfides and thioureas. Reactions of AgF and trimethyl(perfluoroorgano)‐ and trimethyl(alkynyl)‐silanes offer a convenient approach to the corresponding organosilver derivatives, which are excellent reagents for oxidative organylations of group 12–16 elements. Reactions of AgF and elements of groups 13–16 open a convenient access to the corresponding fluorides. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:561–566, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10102     

Polysiloxane zwitterionomers and related model compounds. I. Synthesis

Polymers containing zwitterions were prepared by reacting γ-propanesultone with polydimethylsiloxane-co-(4,7-diazaheptylmethylsiloxane), which generated substituted di(ammonium-3-propane-sulfonate) groups pendant from the siloxane chain. Their concentration in the polymers varied from 0.5 to 10 mole %. Two model compounds were also prepared in order to (1) characterize the reaction leading to the formation of these zwitterions and (2) characterize the ionic forces in solutions (tetrahydrofuran and benzene were used as solvents). The degree of aggregation of these model compounds was higher in tetrahydrofuran and increased in both solutions with the concentration. No rearrangements of siloxane bonds were observed in the presence of these zwitterions or γ-propanesultone.     

Organosilicon compounds I. A novel synthesis of organosilicon substituted furfurals

The use of the diethylacetal moiety of 2-furfuraldiethylacetal as a carbonyl blocking agent during n-butyllithium metalations is described. The synthesis of 5-silicon substituted furfurals is accomplished for the first time with NMR data being employed as a means of structure proof. Furthermore, the isolation of the uniquely stable organo-lithium salt, 5-lithio-2-furfuraldiethylacetal, is reported.