In:
Chemistry – A European Journal, Wiley, Vol. 23, No. 58 ( 2017-10-17), p. 14485-14499
Abstract:
The addition of phosphinoboronate ester Ph 2 PBpin (pin=1,2‐O 2 C 2 Me 4 ) ( 1 ) to a number of different N ‐heterocycles has been investigated. Reaction of 1 with pyridine resulted in highly selective formation of the corresponding 1,4‐addition product, with addition of the electron‐deficient Bpin group to the pyridine nitrogen atom and the phosphido group to the para carbon atom. Conversely, reactions of para ‐substituted pyridine derivatives occurred predominately to afford 1,2‐addition products while quinoline reacted to afford the 1,2‐adduct which ultimately isomerized to afford the corresponding 1,4‐addition product. Preliminary computational studies have been undertaken to explore possible pathways for these transformations including transfer of the PPh 2 − anion from [B(PPh 2 ) 2 pin] − to the 4‐position of a borenium/boronium activated pyridine and concerted pathways for 1,2‐addition via intramolecular nucleophilic attack of PPh 2 at C2 of a Ph 2 PBpin‐coordinated pyridine via a four‐centered transition state and intramolecular transfer of PPh 2 to the 2‐position of a boron‐activated pyridine in a phosphido‐bridged dimer involving a six‐centered transition state.
Type of Medium:
Online Resource
ISSN:
0947-6539
,
1521-3765
DOI:
10.1002/chem.201702203
Language:
English
Publisher:
Wiley
Publication Date:
2017
detail.hit.zdb_id:
1478547-X
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