(±)-2,2′-Bis(diphenylphosphino)-3,3′-binaphtho[2,1-b]furan (BINAPFu) was synthesized from 2-naphthoxyacetic acid in a five-step sequence in 62% overall yield. A variety of reported resolution procedures for biaryl bisphosphines did not work with (±)-BINAPFu; thus, a new resolution method was developed, involving the Staudinger reaction of the aforementioned racemate of BINAPFu with an enantiopure camphor sulfonyl azide derivative. The resulting diastereomeric phosphinimines were separated by flash chromatography. Subsequent hydrolysis to the corresponding bis-phosphine oxide and trichlorosilane reduction provided enantiopure BINAPFu. The absolute stereochemical configuration of BINAPFu was established by X-ray crystallography. BINAPFu was compared with commercially available 2,2′-bis(diphenylphosphino)-1,1′-binaphthalene (BINAP) in Pd(0)-catalyzed intermolecular Heck reactions. Investigation of the Heck arylation of 2,3-dihydrofuran showed BINAPFu to be more efficacious than BINAP in dioxane at 30 °C. A variety of phosphorus selenides were prepared, and the 1JP-Se coupling constants measured, to obtain a comparative scale of parent phosphine basicity. The phosphorus atoms in BINAPFu were found to be electron deficient when compared with BINAP but slightly more electron rich than trifurylphosphine. Key words: naphthofurans, atropisomers, electron-deficient phosphines, asymmetric Heck reactions, Staudinger reaction.
(±)-2,2′-双(
二苯基膦基)-3,3′-双
萘[2,1-b]
呋喃(BINAPFu)是从
2-萘氧乙酸经过五步反应合成,总产率为62%。许多报道的对联
双膦酯的分离方法对(±)-BINAPFu无效;因此,开发了一种新的分离方法,涉及BINAPFu的上述外消旋体与手性纯的
樟脑磺酰
叠氮化合物进行Staudinger反应。通过快速色谱法分离出产物的异构
磷亚胺。随后的
水解得到相应的
双膦氧化物,经三
氯硅烷还原得到手性纯的BINAPFu。通过X射线晶体学确定了BINAPFu的绝对立体
化学构型。在Pd(0)催化的分子间Heck反应中,将BINAPFu与市售的2,2′-双(
二苯基膦基)-1,1′-双
萘烷(BINAP)进行比较。研究
2,3-二氢呋喃的Heck芳基化反应表明,在30°C的二
甲醚中,BINAPFu比BINAP更有效。制备了多种
磷硒化合物,并测量了
1J
P-Se偶合常数,以获得父膦碱度的比较尺度。与BINAP相比,BINAPFu中的
磷原子被发现是电子亏缺的,但比三呋烷基膦富含电子略多。关键词:
萘呋喃、对映异构体、电子亏缺
磷化合物、不对称Heck反应、Staudinger反应。