ABSTRACT
Rhodium(I)/Binap complexes catalyze highly enantioselective additions of methyl- and arylaluminum reagents to cyclic α,ß-unsaturated N-tosyl ketimines. Depending on the solvent and substituents at the ring, the reaction occurs either in a 1,2-manner to deliver α-tertiary allylic amines or in a 1,4-manner to yield, after subsequent reduction, 3-substituted cycloalkyl amines. Well known in the case of the respective cycloalkenones, these first transformations of the aza-analogues enable the synthesis of amine structures of pharmaceutical and biochemical interest.
Subject(s)
Aluminum/chemistry , Coordination Complexes/chemistry , Imines/chemistry , Indicators and Reagents/chemistry , Naphthalenes/chemistry , Nitriles/chemistry , Rhodium/chemistry , Catalysis , Molecular Structure , StereoisomerismABSTRACT
BACKGROUND: Large intrathoracic airway defects may be closed using a pedicled latissimus dorsi (LD) flap, with rewarding results. This study addresses the question of whether this holds true for extrathoracic non-circumferential tracheal defects. METHODS: A cervical segment of the trachea of 4 x 1 cm was resected in 9 white male pigs. The defect was stented with a silicone stent for 3 months and closed either by an LD flap alone (group a, n = 3), an LD flap with an attached rib segment covered by pleura (group b, n = 3), or an LD flap reinforced by a perforated polylactide (MacroPore) plate (group c, n = 3). The trachea was assessed by rigid endoscopy at 3 and 4 months and histologically at 4 months postoperatively. RESULTS: The degree of stenosis at the level of the reconstruction at 4 months was 25, 50 and 75% in group a, 15, 50 and 60% in group b, and 20, 95 and 95% in group c, respectively. The percentage of the defect covered by columnar epithelium was 100% in all animals of group a, 60, 100 and 100% in group b, and 10, 0 and 0% in group c. Resorption of the rib was seen in all animals of group b and obstructive inflammatory polyps were found in 2 animals of group c. CONCLUSION: Pedicled LD flaps provided less satisfactory results for closure of large non-circumferential extrathoracic airway defects than observed after intrathoracic reconstruction. A pedicled rib segment added to the LD flap did not improve the results obtained from LD flap repair alone, and an embedded MacroPore prosthesis may result in severe airway stenosis due to plate migration and intense inflammatory reaction protruding into the tracheal lumen.
