Cyclopropylideneacetates (2a,b) undergo a formal [2 + 4] cycloaddition with (diphenylmethylene)amine (DPMA-H)(1) to yield dihydro-1-phenylisoquinoline-4-carboxylate (8a) and 1-phenylisoquinoline-4-carboxylate (7b); the Michael adduct of DPMA-H onto (2b), on the other hand, under basic conditions gives 1-phenyl-2-aza-azulene-3a-carboxylate (12) exclusively.

The syntheses and reactivities of some new cyclopropane containing C5-building blocks with composite functionalities are described. Recent applications of cyclopropylideneacetates in short syntheses of spirocyclopropane-annulated heterocycles and cyclopropane-containing biologically active compounds are demonstrated. Cyclopropylacetylenes are employed as cyclopentane annulation reagents and are particularly useful in the construction of terpenoid frameworks. 1. Introduction 2. The Initial Experiment: 1-Chloro-1-(trichlorovinyl)cyclopropanes from Olefins 3. Cyclopropylideneacetates 4. Cyclopropylacetylenes 5. Conclusion

Cyclopropylideneacetates (2a,b) undergo a formal [2 + 4] cycloaddition with (diphenylmethylene)amine (DPMA-H)(1) to yield dihydro-1-phenylisoquinoline-4-carboxylate (8a) and 1-phenylisoquinoline-4-carboxylate (7b); the Michael adduct of DPMA-H onto (2b), on the other hand, under basic conditions gives 1-phenyl-2-aza-azulene-3a-carboxylate (12) exclusively.

The syntheses and reactivities of some new cyclopropane containing C5-building blocks with composite functionalities are described. Recent applications of cyclopropylideneacetates in short syntheses of spirocyclopropane-annulated heterocycles and cyclopropane-containing biologically active compounds are demonstrated. Cyclopropylacetylenes are employed as cyclopentane annulation reagents and are particularly useful in the construction of terpenoid frameworks. 1. Introduction 2. The Initial Experiment: 1-Chloro-1-(trichlorovinyl)cyclopropanes from Olefins 3. Cyclopropylideneacetates 4. Cyclopropylacetylenes 5. Conclusion

Cyclopropylideneacetates (2a,b) undergo a formal [2 + 4] cycloaddition with (diphenylmethylene)amine (DPMA-H)(1) to yield dihydro-1-phenylisoquinoline-4-carboxylate (8a) and 1-phenylisoquinoline-4-carboxylate (7b); the Michael adduct of DPMA-H onto (2b), on the other hand, under basic conditions gives 1-phenyl-2-aza-azulene-3a-carboxylate (12) exclusively.

The syntheses and reactivities of some new cyclopropane containing C5-building blocks with composite functionalities are described. Recent applications of cyclopropylideneacetates in short syntheses of spirocyclopropane-annulated heterocycles and cyclopropane-containing biologically active compounds are demonstrated. Cyclopropylacetylenes are employed as cyclopentane annulation reagents and are particularly useful in the construction of terpenoid frameworks. 1. Introduction 2. The Initial Experiment: 1-Chloro-1-(trichlorovinyl)cyclopropanes from Olefins 3. Cyclopropylideneacetates 4. Cyclopropylacetylenes 5. Conclusion