Gold(I)-Catalyzed 7-exo-dig Cyclization: A Key Step to Access the Bicyclo[4.2.1]nonane Skeleton of Vibsatin A, a Neurotrophic Diterpenoid

Vibsatin A is a new neurotrophic vibsane-type diterpenoid comprising a bridged bicyclo[4.2.1]nonane skeleton. Inspired by Sawamura's works, we generated the bicyclic backbone through a Conia-ene-derived 7-exo-dig cyclization from an enantiomerically enriched TIPS-based silyl enol ether. The reaction, catalyzed by a sensitive gold(I) complex, was efficiently performed on a large scale by glovebox free techniques. Furthermore, the shape of this system was exploited for subsequent installation of all of the stereogenic centers.

Silver(I) Oxide-/DBU-Promoted Synthesis of Dihydrofuran Units through Allenyl Silver Formation

A formal [3+2] cyclization mediated by silver(I) oxide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is described herein. Through a broad variety of carbonyl compounds, this system can promote cyclization reactions with high yield (up to 85 %) and diastereoselectivity (up to 95:5) for a straightforward access to complex and congested dihydrofuran derivatives in one step under mild conditions. Based on DFT studies, the proposed mechanism would involve an allenyl silver intermediate.

Ti(II) and Rh(I) Complexes as Reagents toward a Thapsigargin Core

A novel approach toward the [5-7]fused bicyclic core of thapsigargin, a subnanomolar inhibitor of the endo/sarcoplasmic calcium ATPase (SERCA), is presented. The synthetic route includes an original Ti(II)-mediated hydroxy-directed reductive coupling of an enantiomerically enriched propargylic alcohol and an intramolecular Rh(I)-catalyzed cyclocarbonylation reaction as key steps. Interestingly, through the first experiments of titanocene-mediated reductive cyclization of a 1,8-enyne, a seven-membered cycle was isolated as a unique product with a total diastereoselectivity.

Natural products and ring-closing metathesis: synthesis of sterically congested olefins

This review highlights RCM reactions towards the synthesis of sterically congested natural products throughout the recent evolution of catalysts.

Recent advances in the synthesis of natural multifunctionalized decalins

This review highlights recent innovative synthetic strategies developed for the stereoselective construction of natural complex decalin systems. It offers an insight into various synthetic targets and approaches and provides information for developments within the area of natural products as well as synthetic methodology.

Cutaneous metastasis of lung carcinoma: a retrospective study of 12 cases

BACKGROUND

The skin is a rare site of metastasis of the internal malignancies. On the contrary, lung cancer is a common primary malignancy of skin metastasis. The latter is either synchronous with the primary lung tumour or can reveal it.

OBJECTIVE

To analyse the clinical findings and the outcome of cutaneous metastasis in patients with primary lung cancer.

METHODS

Retrospective study including 12 cases of cutaneous metastasis of lung cancer diagnosed in our institution during 6years.

RESULTS

Our patients included three women and nine men with a median age of 59.83years. The cutaneous metastases were unique in seven cases. They revealed the primary tumour in two cases, were discovered synchronously with the primary tumour in six cases and after the primary tumour in four cases. They appeared in patients presenting multiple metastases in 10 cases. Clinical appearance consisted on a firm nodule, sometimes ulcerated with a diameter ranging from 0.5 to 5.5cm. The tumour was sited in the thorax, the back, the abdomen; or the upper or lower limbs. Pathological examination of bronchial biopsy revealed an adenocarcinoma in eight cases, a squamous cell carcinoma in two cases and a small cell carcinoma in two cases. In spite of lung cancer therapies, the patients with metastasis to other organs with a median follow-up time of 4months died.

CONCLUSION

Cutaneous metastases of lung cancer are of poor prognosis. They are most of the time associated with an advanced neoplastic process with metastasis to other organs. Median survival after skin involvement does not exceed months.