Synthesis, characterization and chemistry of platinum complexes derived from cyclopropanes with electron donors.

摘要

It has long been known that Zeise's Dimer inserts into cyclopropanes to form platinacyclobutanes. However, not all platinacyclobutanes are stable, and several have been shown to form novel organic products. It has also been shown that pi electron donors on the cyclopropone will stabilize the incipient carboncation formed by the platinacyclobutane. Various tactics can then be used to further direct the chemistry.;The first thrust of this research utilized strained ring systems to affect the chemistry about the platinacyclobutane. In the first example, 2,7,7-trimethyltircyclo(4.1.1.0;A second method utilized in the stabilization of the incipient carbocation generated by a platinacyclobutane is the use of an olefin alpha to the cyclopropane. Platinacyclobutanes from these systems undergo a rearrangement to form methylene tethered pi allylic complexes which have the unique ability to undergo a variety of regio and stereo-selective nucleophilic additions without decomposition of the complex. These complexes can then be decomposed utilizing a variety of methods yielding a plethora of interesting organic products based on the original diene that the cyclopropane was generated from.;A third method used to direct the chemistry resulting from platinacyclobutanes is the use of the lone pair of electrons on a heteroatom, in this case sulfur and nitrogen. Both demonstrate the ability of a hetero atom to direct the chemistry of platinacyclobutanes. However in the case of amino cyclopropane, the nitrogen complexes to one platinum atom before a second inserts and thereby prevents chemistry alpha to the amine. In the case of phenyl cyclopropyl sulfide, the addition of Zeise's Dimer yields a rearrangement of the cyclopropane to a propenyl moiety.;In all cases, it was shown that the nature of the platinum carbon bond polarization in a platina(IV)cyclobutane is platinum minus carbon plus. Also, this thesis helps define how pi donating substituents on cyclopropanes direct the subsequent chemistry of platinacyclobutanes formed from these cyclopropanes.