1,2-Thiaborolide:  A New Heteroaromatic π-Ligand Containing Boron and Sulfur

Abstract

The heteroaromatic anion lithium 2-(diisopropylamino)-1,2-thiaborolide (3) has been prepared by a synthesis using the Grubbs ring-closing metathesis. 3 has been converted to the Cp*Ru complex 10, the Cp*ZrCl2 complex 11, and the Me2Si-bridged CpZrCl2 complex 15.

A 1,3-Dihydro-1,3-azaborine Debuts

“…8 Deprotonation of n- Bu 3 SnH with LDA followed by addition of the mixture of 5 and 5 ’ furnished 6 in 72% yield, with the 1,2,3-benzotriazole serving as a leaving group. 9 Our initial attempts using direct transmetallation between stannane nucleophile 6 and the vinylboron chloride 7 10 were unsuccessful. However, lithium-tin exchange of 6 with n -hexyllithium followed by addition of electrophile 7 afforded the desired coupling product 8 in 67% yield.…”

2H-1,2-Thiaborin: A New Boron–Sulfur Heterocycle

“…Subsequent ring expansion followed by loss of chloride affords 2c , as illustrated in Scheme . It had been previously found that the C(5) position of 6 is more nucleophilic than C(3) . We speculate that any chlorocarbene attack at C(5) (path b) does not lead to low-molecular-weight products but is responsible for the relatively modest yield of 2c.…”

“…The synthesis of 2c involves an extension of the carbenoid ring-expansion route we have previously used to prepare 1b , and the analogous boron–oxygen heterocycle 4b. The treatment of the readily available 2,5-dihydro-2-(diisopropylamino)-1,2-thiaborole 5 with 2 equiv of LDA in THF followed by reaction with excess methylene chloride gave a 15% yield of 2c. The 2 H -1,2-thiaborin 2c was distilled from the reaction mixture and isolated as a pale yellow oil, which solidified to nicely formed blocklike crystals: mp 21 °C.…”

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“…An ansa-type ligand derived from the thiaborole has also been reported. 130 The syntheses and structures of Mg(h 6 -C 5 H 5 BMe) 2 and Mg(h 6 -3,5-Me 2 C 5 H 3 BNMe 2 ) 2 have been reported along with the adduct species Mg(h 6 -C 5 H 5 BMe)(h 1 -C 5 H 5 BMe)-(bipy) and Mg(3,5-Me 2 C 5 H 3 BNMe 2 ) 2 (THF) 2 , in which the boratabenzene adopts a novel s bonding mode to the magnesium. 131 Reaction of CrCl 3 (THF) 3 with various borabenzenes Li(C 5 H 5 BR) (R = Me, NMe 2 or Ph) affords the chromium(II) sandwich complexes Cr(h 6 -C 5 H 5 B-R) 2 .…”