Benzo(B)Thiophene → 2-Bromobenzo(b)thiophene

Participants

Reaction Steps

Starting from the commercially available 3-bromobenzo[b]thiophene (5), a synthetic route to poly(2,2′-bisbenzo[b]thiophene) (4) is outlined below in Scheme 1. 3-bromobenzo[b]thiophene (5) is alkylated to (6) using an alkyl grignard and Ni(dppp)Cl2. Benzo[b]thiophene (6) is brominated at the 2-position using n-butyllithium followed by bromine to yield (7). 2-Bromobenzo[b]thiophene (7) is homo-coupled using a liganded nickel complex reducing agent (generated from NaH, t-AmONa, Ni(OAc)2 and bipyridine) to yield 2,2′-bisbenzo[b]thiophene (2). Bromination of 2,2′-bisbenzo[b]thiophene (2) with N-bromosuccinimide or bromine water yields 5-5′-dibromo 2,2′-bisbenzo[b]thiophene (8).

Provenance & Evidence