1,3-Benzothiaborolide:  A New Heteroaromatic Anion

Abstract

Lithium N,N-diisopropyl-3-amino-1,3-benzothiaborolide (5) was prepared by a multistep synthesis starting from thioanisole. The thiaborolide 5 was converted to a Cp*Ru η5-adduct, which was characterized by X-ray diffraction.

1,3-Thiaborolide: A New Heteroaromatic Surrogate for Cyclopentadienide

“…16 The 1 H and 13 C NMR spectra of 5 at ambient temperature show that the two isopropyl groups are identical due to rapid rotation about the B-N bond. As had previously been found for 6 7 and lithium aminoboratabenzenes, 14,17 the strong C-B π-bonding of the aromatic ring diminishes the ability of boron to π-bond to the exocyclic nitrogen. Interestingly the 1 H NMR signals (δ 6.19, 6.95) and the 13 C NMR signal (δ 126.8, 132.2) for the CH groups at C(4) and C(5), respectively, are in the normal aromatic/olefinic region.…”

“…The only prior work on 5 involves the recent synthesis of benzo-1,3-thiaborolide 6. 7 We now wish to report on the first synthesis of a monocyclic thiaborolide 5 and on its conversion to metal complexes 7 and 8.…”

“…The thiaborolide ring is η 5 -bound to Ru in the same manner found for the corresponding complex of 6. 7 Although a partial disorder between S(1) and C(2) limits the accuracy of the bond distances, the structural data clearly (8) Experimental procedures and characterization of new compounds are as follows: (a) 3,3-Dibutyl-2,3-dihydro-1,3-thiastannole ( 12): An aqueous solution of 75% (w/w) Bu4NF (20 mL, 49.3 mmol) was added dropwise to a solution of chloromethyl trimethylsilylethynyl sulfide (8.0 g, 44.9 mmol) in 10 mL of methanol at 0 °C. The resulting mixture was allowed to stir at 0 °C for 2 h. Ice cold H2O was added, and the mixture was extracted with pentane.…”

“…Since 1,3-thiaborolide 5 is similarily derived from thiophene, an exploration of the coordination chemistry of 5 is an attractive goal. The only prior work on 5 involves the recent synthesis of benzo-1,3-thiaborolide 6 . We now wish to report on the first synthesis of a monocyclic thiaborolide 5 and on its conversion to metal complexes 7 and 8 .…”

Preparation of Thioanisole Biscarbanion and C–H Lithiation/Annulation Reactions for the Access of Five-Membered Heterocycles

“…We initiated our studies by investigating the formation of dianions on substituted arene at both the lateral and ortho -positions. Attempts on the lithiation of thioanisole 1 with 2.0 equiv of organolithium reagent (nBuli, sBuli, or tBuLi) in ethereal solvent (Et 2 O or THF) at low temperature (−78 °C) were not fruitful; no dianion was observed. Interestingly, when a solution of arene 1 was treated with 1.0 equiv of nBuLi with an equal molar amount of TMEDA in hexane at 65 °C, followed by trapping the reaction mixture with TMSCl as the eletrophile, a mixture of of silane 1-b and bissilane 1-c was detected, and the corresponding silanes 1-b and 1-c were isolated in 81% and 9% yields, respectively (Supporting Information, Scheme ).…”