An iterative approach to higher polyquinanes

A simple cyclopentane annulation strategy has been developed using inexpensive reagents. Starting from the readily available bicyclo[3.3.0]octane system several polyquinanes were prepared by iterative annulation procedure and herein we report a short and a convenient route to a new C20-hexaquinane system

Synthetic approach to linearly annulated tetralin-based constrained α-amino acid derivatives via Rongalite

Tetralin-based α-amino acid derivatives were assembled through the application of Diels-Alder reaction as a key step. Here, Rongalite has been used to generate the key o-xylylene intermediate

Synthesis of cage heterocycles containing tetrahydrofuran and pyran ring system via Grignard addition and ring-closing metathesis

75-84Several cage compounds containing tetrahydrofuran and pyran rings have been reported by using the Grignard addition and ring-closing metathesis as key steps. Cage hemiketal derivatives have been generated due to the proximity of two carbonyl groups in cage dione. These cage heterocycles have been derived from readily available starting materials such as 1,4-hydroquinone and dicyclopentadiene

Synthesis of cage heterocycles containing tetrahydrofuran and pyran ring systemvia Grignard addition and ring-closing metathesis

Several cage compounds containing tetrahydrofuran and pyran rings have been reported by using the Grignard additionand ring-closing metathesis as key steps. Cage hemiketal derivatives have been generated due to the proximity of twocarbonyl groups in cage dione. These cage heterocycles have been derived from readily available starting materials such as1,4-hydroquinone and dicyclopentadiene

Synthetic approach to oxa-triquinanes via olefin metathesis as a key step

Earlier, a simple synthetic approach to cis, syn, cis-triquinanes and propellanes from exo-nadic anhydride through metathesis approach had been demonstrated. In the present work is discussed a distinct course of observations when this methodology has been extended to oxygenated exo-nadic anhydride derivatives and the importance of stereochemistry and the role of hetero atom in the outcome of olefin metathesis has been demonstrated

Synthesis of spiro-annulated cyclobutane derivatives through ketene [2+2] cycloaddition and ring-rearrangement metathesis

Herein is reported a concise synthesis of spiro-annulated cyclobutane tetracyclic and pentacyclic derivatives by ketene addition, and ring-rearrangement metathesis (RRM) as key steps, starting with commercially available norbornadiene and dicyclopentadiene. The tetracyclic spiro-derivative contains a [5/5/4] core unit, which is the key building block to angular triquinanes synthesis. Whereas, the pentacyclic spiro-derivative contains a basic core skeleton of presilphiperfolanes, and other sesquiterpenoids

Synthetic approach to oxa-triquinanes via olefin metathesis as a key step

1868-1874Earlier, a simple synthetic approach to cis, syn, cis-triquinanes and propellanes from exo-nadic anhydride through metathesis approach had been demonstrated. In the present work is discussed a distinct course of observations when this methodology has been extended to oxygenated exo-nadic anhydride derivatives and the importance of stereochemistry and the role of hetero atom in the outcome of olefin metathesis has been demonstrated

Synthesis of spiro-annulated cyclobutane derivatives through ketene [2+2] cycloaddition and ring-rearrangement metathesis

1875-1880Herein is reported a concise synthesis of spiro-annulated cyclobutane tetracyclic and pentacyclic derivatives by ketene addition, and ring-rearrangement metathesis (RRM) as key steps, starting with commercially available norbornadiene and dicyclopentadiene. The tetracyclic spiro-derivative contains a [5/5/4] core unit, which is the key building block to angular triquinanes synthesis. Whereas, the pentacyclic spiro-derivative contains a basic core skeleton of presilphiperfolanes, and other sesquiterpenoids

Synthesis of cis-syn-cis and cis-anti-cis linear triquinanes via photo-thermal metathesis

Diverse cis-syn-cis and cis-anti-cis triquinane frameworks have been assembled by a simple synthetic protocol starting with substituted cage diones under microwave irradiation conditions. Thermal fragmentation of the cyclobutane ring play a key role in this process and milder reaction conditions have been employed in contrast to normal flash vacuum pyrolysis conditions. Here, thermal isomerization of the double bond has also been realized under the microwave irradiation conditions to afford the isomeric triquinanes at low temperature. These triquinane units are considered to be useful for the total synthesis of natural products and non-natural products containing fused cyclopentane rings

Synthesis of cis-syn-cis and cis-anti-cis linear triquinanes via photo-thermal metathesis

1556-1563Diverse cis-syn-cis and cis-anti-cis triquinane frameworks have been assembled by a simple synthetic protocol starting with substituted cage diones under microwave irradiation conditions. Thermal fragmentation of the cyclobutane ring play a key role in this process and milder reaction conditions have been employed in contrast to normal flash vacuum pyrolysis conditions. Here, thermal isomerization of the double bond has also been realized under the microwave irradiation conditions to afford the isomeric triquinanes at low temperature. These triquinane units are considered to be useful for the total synthesis of natural products and non-natural products containing fused cyclopentane rings