134179-01-4Relevant articles and documents
Studies of π-diastereofacial selectivity: Spiro 2-tetrahydrofuran and 2-tetrahydrothiophene ketones
Dimitroff, Martin,Fallis, Alex G.
, p. 2531 - 2534 (1998)
The facial influence and synthetic utility of oxygen, sulfur and carbon atoms adjacent to the ketone in the series of α-spiro ketones 2, 3, and 4 upon nucleophilic addition has been examined. Addition to the carbonyl group displayed a preference for attack anti to the heteroatom in competition with carbon in synthetically useful ratios. Hydride reduction of 2 with chelating reagenst (NaBH4, LiAlH4 etc.) reversed this facial preference.
Bronsted acid catalyzed enantioselective semipinacol rearrangement for the synthesis of chiral spiroethers
Zhang, Qing-Wei,Fan, Chun-An,Zhang, Hai-Jun,Tu, Yong-Qiang,Zhao, Yu-Ming,Gu, Peiming,Chen, Zhi-Min
supporting information; experimental part, p. 8572 - 8574 (2009/12/29)
A new twist: The catalytic asymmetric semipinacol rearrangement reaction of 2oxo allylic alcohols 1 in the presence of a catalytic amount of chiral phosphoric acid (R)-2a or its silver salt (R)-2b affords enantiomerically pure spiroethers 3.
Synthesis and Molecular Structure of Belted Spirocyclic Tetrahydrofurans, A New Class of Preorganized Hosts for Cations
Paquette, Leo A.,Negri, Joanna T.,Rogers, Robin D.
, p. 3947 - 3956 (2007/10/02)
The preparation and binding properties of spirocyclic tetrahydrofurans 7-11 are described.The condensation of cyclopentanone with 5-lithio-2,3-dihydrofuran (12) provided an alcohol which readily rearranged to ketone 14 under acidic conditions. "Capping" of the carbonyl group in 14 so as to generate a second spiro tetrahydrofuran subunit gave rise to 7 and 8.Starting with cyclobutanone, 2-fold ring expansion involving 12 provided the key reactions leading to 22 and 23, which were "capped" as before.Crystal structure data are available for 9, 11, and 22.In addition, the variable-temperature NMR behaviour of 7 and 10 was quantified by means of 2-D measurements.A detailed analysis is presented that shows the gauche effect to be of major importance in dictating the major conformation adopted by these ionophores.The binding properti s of 7 - 11 have been assayed.Considerable variation was found, the efficiency being critically dependent upon the number of oxygen atoms, the relative stereochemistry of the C-O bonds, and the relative ease of conformational readjustment necessary to achieve proper organization around the oxophilic metal ion.