Lewis and Brønsted basicity of phosphine-diazomethane derivatives

Abstract

The compounds EtOC([double bond, length as m-dash]O)CHNNPR3 (R = Ph 1, Cy 2, tBu 3) were prepared via the reactions of the diazomethane and a phosphine. In subsequent reactions with B(C6F5)3, the compounds 2 and 3 are shown to exhibit Lewis basicity at the carbonyl oxygen affording EtOC([double bond, length as m-dash]O(B(C6F5)3))CHNNPR3 (R = Cy 5, tBu 6). Reactions of 5 and 6 with water or phenol illustrated the Brønsted basicity at the nitrogen atom adjacent phosphorus, affording the compounds, [EtOC([double bond, length as m-dash]O)CHNNHPR3][HOB(C6F5)3] (R = Cy 7, tBu 8) and [EtOC([double bond, length as m-dash]O)CHNNHPR3][PhOB(C6F5)3] (R = Cy 9, tBu 10), respectively. The formulation of these products is confirmed via spectroscopic and crystallographic studies, and insight is garnered from computations.

Facile proton-coupled electron transfer enabled by coordination-induced E–H bond weakening to boron

“…B(1)-S(1) (1.960(avg) Å) and B(1)-O(1) (1.476(10) Å) are similar to reported aryl-sulfide and -oxide bond lengths 25,26. These reactions indicate formal loss of H• and attempts to detect possible H 2 formation by 1 H or 2 H NMR spectroscopy -the latter using the C 6 F 5 OD isotopologue -revealed no H 2 (or D 2 ) in either case (Figs.S47-S49).…”

Reactions of Frustrated Lewis Pairs with Chloro‐Diazirines: Cleavage of N=N Double Bonds

“…[8] However, in 2017, we isolated the unstable Ph 2 CN 2 B(C 6 F 5 ) 3 [9] which was subsequently stabilized by single electron reduction, leading to radical‐based intra‐ or intermolecular C−H bond activation [10] . In parallel studies, we and others also showed that diazoesters [11] and diazonium cations [12] reacted with phosphine donors, affording adducts of the form EtOC(=O)CHNN(PR 3 ), [ArN(PPh 3 )N(PPh 3 )] + and [ArN 2 (PR 3 )] + , respectively. Subsequently, related chemistry of boranes and diazoesters has been exploited in organic synthesis by Melen and co‐workers [13] .…”

2,5,8,11-Tetramethyl-2,5,8,11-tetraazadodecane-2,11-diium bis[hydroxytris(pentafluorophenyl)borate] benzene 2.5-solvate

“…As a strong Lewis acid, it readily forms salts with bases such as amines. A search of the Cambridge Structural Database (CSD version 5.41, November 2019; Groom et al, 2016) for structures containing amine salts of hydroxy [tris-(pentafluorophenyl)]borate gave 13 hits [DOJSAX (Peters et al, 2008); GIZZIZ ; ITULOA (Tao et al, 2016); KERLUO (Duchateau et al, 2000); MUQMUG (Drewitt et al, 2002); OFAFUZ (Schneider et al, 2018); OZUBUH (Kelsen et al, 2011); PEGCUA (Focante, Camurati et al, 2006); QIMKUS (Stibrany & Brant, 2001); RAQWAI (Saverio et al, 2005); SEFDIR (Hewavitharanage et al, 2005); UXIJIW, UXIJUI (Thakur et al, 2016)]. However, there were no hits for the dication.…”