Under CuBr·SMe2/PPh3 catalysis (5/10 mol‐%) RMgCl (R = Me, Et, nPr, CH=CH2, nBu, iBu, nC5H11, cC6H11, Bn, CH2Bn, nC11H23) readily (–78 °C) undergo 1,4‐addition to Cbz or Boc protected quinolin‐4(1H)‐ones to provide 2‐alkyl‐2,3‐dihydroquinolin‐4(1H)‐ones (14 examples, 54–99 % yield). Asymmetric versions require AlEt3 to Boc‐protected ethyl 6‐substituted 4(1H)‐quinolone‐3‐carboxylates (6‐R group = all halogens, n/i/t‐alkyls, CF3) and provide 61–91 % yield, 30–86 % ee; any halogen, Me, or CF3 provide the highest stereoselectivities (76–86 % ee). Additions of AlMe3 or Al(nC8H17)3 provide ≈ 45 and ≈ 75 % ee on addition to the parent (6‐R = H). Ligand (S)‐(BINOL)P–N(CHPh2)(cC6H11) provides the highest ee values engendering addition to the Si face of the 4(1H)‐quinolone‐3‐carboxylate. Allylation and deprotection of a representative 1,4‐addition product example confirm the facial selectivity (X‐ray crystallography).

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Tracheal webs are known to be a rare complication of prolonged endotracheal intubation. Adults often present with signs of obstructive lung disease. We present the case of a 21-year-old female with acute hypercapnic respiratory failure secondary to severe (90%) tracheal webbing. CASE PRESENTATION: The patient presented to the hospital with CC of shortness of breath for 3 days. Her PMH is significant for MVC with poly-trauma 5 months earlier; her hospitalization was complicated by ventilator dependence, requiring tracheostomy after 17 days. She was decannulated 19 days after tracheostomy placement. Following discharge, the patient presented to the ED on 3 separate occasions with SOB. She was evaluated by ENT at each visit with direct laryngoscopy demonstrating patent glottis and normal vocal cord function. CT neck/thorax was performed 4 days prior to this presentation; it was notable for an existing tracheal diverticulum but no stenosis. On the day of presentation, the patient was in respiratory distress with hypercapnia. Initially she was started on BIPAP and treatment for acute asthma exacerbation, but continue to show worsening hypercapnia. She was emergently intubated and there was significant difficulty with bag mask ventilation after intubation. There were very high peak pressures when connected to the ventilator and only very small volumes were being delivered. Chest x-ray revealed the ETT was 5 cm above the carina with normal lung parenchyma. Emergent bronchoscopy was performed which showed 90% stenosis of the trachea at the level of the ETT tip. An emergent balloon dilation of the subglottic tracheal web was performed. The patient's tracheal web, while significant in diameter, was very thin and amenable to dilation. Her respiratory acidosis correctly quickly after dilation of the web and she was extubated about 8 hours after dilation without complication. DISCUSSION: Prolonged intubation and tracheostomy is a known risk for tracheal web formation and can occur in 1-22% of patients [1]. Hypercapnia respiratory though is an unusual complication of tracheal stenosis. In order for tracheal stenosis to become symptomatic, up to 50% needs to be occluded, and mostly presents with shortness of breath, stridor and obstruction on flow-volume loops [2,3]. Using a pubmed review, there are few case reports of patients with hypercapnia with tracheal stenosis. Of the three found, one was preceded by intubation, one congenital and one from extrinsic compression by a mass [4,6]. In one case, the patient was also prescribed non-invasive ventilation and had worsening hypercapnia requiring intubation [5]. CONCLUSIONS: This case represents an unusual cause of hypercapnic respiratory failure and should be a diagnosis to consider with patient who fail non-invasive ventilation, especially with a history of intubation.

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