Wormholes through chemical space: Spirocyclic oxetanes are described as analogues of morpholine and also as topological siblings of their carbonyl counterparts. They are particularly promising in terms of both their physicochemical properties and the ease with which they can be grafted onto molecular structures. The data collected highlight oxetanes as both the hydrophilic sister of a gem‐dimethyl unit and the carbonyl group's lipophilic brother.

Significant iatrogenic bleeding during flexible bronchoscopy is fortunately rare and usually self-limiting. Life-threatening bleeding, however, can occur, especially after conventional or cryoprobe-assisted transbronchial biopsy. The aim of this review is to provide the practising pulmonologist with a concise overview of the incidence, severity and risk factors for bleeding, to provide sensible advice on prophylactic measures and to suggest a plan of action in the case of significant bleeding. Bronchoscopy units should have a standardised approach and plan of action in the case of life-threatening haemorrhage. Wedging the bronchoscope in the bleeding segment, turning the patient in an anti-Trendelenburg position and onto the side in order for the bleeding lung to be in the dependent position, installing vasoconstrictors and using a tamponade balloon early are the recommended first-line strategies. Involving a resuscitation team should be considered early in the case of massive bleeding, desaturation and haemodynamic instability.

Wurmlöcher im chemischen Raum: Spirocyclische Oxetane werden als Analoga von Morpholin und als topologische Gegenstücke entsprechender Carbonylverbindungen beschrieben. Solche Oxetane sind vielversprechend bezüglich ihrer physikochemischen Eigenschaften und der Leichtigkeit, mit der sie in Molekülstrukturen eingebaut werden können. Die gesammelten Daten präsentieren die Oxetan‐Gruppe einerseits als hydrophile Entsprechung einer geminalen Dimethyleinheit und andererseits als lipophile Entsprechung einer Carbonylgruppe.

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