Cu(I) catalysed cyclopropanation of olefins: Stereoselectivity studies with Arylid-Box and Isbut-Box ligands

Covalent and Noncovalent Immobilization of Arylid‐BOX Ligands and Their Derivatives: Evaluation in the Catalytic Asymmetric Cyclopropanation of Styrenes

“…For this reason an unsuccessful attempt to convert 2-(4-hydroxybenzylidene)-malonic acid (not shown) into the corresponding bis-amide by our standard method [14][15][16] was made. [18] It was assumed that the free hydroxy group was interfering with the reaction.…”

“…Although the TBDMS-protected dimethyl malonate ester 11 was successfully prepared from the p-TBDMS-protected hydroxymethylbenzaldehyde derivative 10, [7] transformation into the corresponding protected diamide alcohol 13 proved impossible despite our best efforts. Acid hydrolysis of the diester 11 by the standard procedure [14][15][16] proved difficult, so we used Scheme 1. Attempted synthesis of 8.…”

“…The p-bromo-Arylid-BOX 15a and p-chloro-Arylid-BOX 15b were prepared under our standard conditions. [14,15] Unfortunately, after much experimentation with a variety of sets of conditions -which included the use of various palladium catalysts [e.g. Pd(OAc) 2 , Pd-(dba) 2 , Pd(dppf) 2 , Pd(PPh 3 ) 4 ], bases, and ligands -it was not possible to obtain the phenylated Arylid-BOX 17a.…”

“…[14] They have shown significant applicability in some asymmetric catalytic reactions, such as styrene cyclopropanations, [15,16] the Friedel-Crafts alkylation of indole with phenylidenemalonates, [17a] and the Henry reaction between nitromethane and benzaldehyde.…”

“…We decided to immobilize our rigid Arylid-BOX family of ligands 6 [14,15] on a Wang resin, expecting their inherent rigidity to lead to good levels of metal binding within the support.…”