Synthesis of novel 2H-spiro[1-benzofuran-3,4′-piperidin]ol scaffolds

Strategies for the synthesis of spiropiperidines – a review of the last 10 years

“…This journal is © The Royal Society of Chemistry 20xx The synthesis of spirocyclic benzofurans bearing a 4spiropiperidine through an intramolecular Heck cyclisation was developed by Leflemme. 47 Bromide 133 was treated with Herrmann-Beller catalyst 134 which underwent intramolecular cyclisation to give benzofuran 135 in high yield (Scheme 36). The cyclisation was demonstrated with different benzyl alcohol substitution around the phenyl ring.…”

Synthesis of Benzofuran Derivatives via Different Methods

“…The method involved a key intramolecular Heck cyclization, which was applied for three series of compounds. The desired scaffolds were obtained in overall yields of 42-53% with retrosynthetic approaches based on the literature [51] (Scheme 15). o-Iodophenol 64 reacted with 1-propargylbenzotriazole 63 in the presence of (PPh 3 ) 2 PdCl 2 , CuI, and Et 3 N to give 2-(benzotriazol-1-ylmethyl) benzo[b]furan 65.…”

Visible-Light-Induced Regioselective Functionalization of α-Olefin: Development of One-Pot Photo-Synthesis of C3-Substituted Dihydrobenzofurans

“…Furthermore, this method can also be used to synthesize a C 3 -spiropiperidinyl DHB such as 3x, which is known to exhibit important biological activities. 15 Both (E)-and (Z)-β-methylstyrene (1y) were reacted under the optimized conditions. Interestingly, C 2 , C 3 -disubstituted DHBs 3y were generated with a single diastereomer with complete regioselectivity, indicating that the stereoselectivity of the product was not affected by the conformation of the starting materials.…”

“…The reaction proceeded smoothly with 1w to give the desired spiro-DHB 3w . Furthermore, this method can also be used to synthesize a C 3 -spiropiperidinyl DHB such as 3x , which is known to exhibit important biological activities . Both (E)- and (Z)-β-methylstyrene ( 1y ) were reacted under the optimized conditions.…”

“…We envisioned the plausible mechanism (Scheme ). Initially, 2a is excited by light and undergoes intersystem crossing to generate n−π* triplet species . Subsequently, the [2 + 2] photocycloaddition proceeds to generate C 3 -substituted oxetane III . ,, There are two possible mechanisms leading to the formation of C 3 -substituted oxetane III : (1) the addition of the triplet diradical leads to the formation of the long-lived biradical I species or short-lived biradical II species, and (2) the formation of a CT-exciplex ,, between the excited triplet 2a and 1a generates the aforementioned diradicals I or II via SET.…”