Phosphabarrelene–rhodium complexes as highly active catalysts for isomerization free hydroformylation of internal alkenes

Abstract

A new class of phosphabarrelene-rhodium catalysts is described which allows for the first time hydroformylation of internal alkenes with very high activity and which proceeds essentially free of alkene isomerization.

1,2‐Diastereoselective C–C Bond‐Forming Reactions for the Synthesis of Chiral β‐Branched α‐Amino Acids

“…Switching to phosphane ligands and starting with triphenylphosphane (C) gave similar results as ligand A (entry 6). Finally, the bulky phosphane ligand phosphabarrelene [26] (D) was found to give the best diastereocontrol and yield favouring the syn isomer 38 (syn/anti = 94:6, Table 5, entries 7 and 8). The relative configuration was determined by correlation with the known syn product formed by the addition of methyl cuprate to 2 (Scheme 1).…”

Highly selective hydroformylation of internal and terminal olefins to terminal aldehydes using a rhodium-BIPHEPHOS-catalyst system

“…Some ligands seem to allow a hydroformylation without any isomerization [4], other ligands isomerize internal olefins first and hydroformylate to yield only the terminal aldehyde [5]. In addition to isomerization, the hydrogenation is an important side-reaction (Scheme 1).…”

Room‐Temperature Palladium‐Catalyzed Negishi‐Type Coupling: A Combined Experimental and Theoretical Study

“…[11] Most recently, we have incorporated the phosphabarrel-A C H T U N G T R E N N U N G ene ligand 1 (= L in Scheme 1 and 2), in various catalytic processes, such as the Pt-catalyzed hydrosilylation of alkynes, or the Pd-catalyzed Suzuki-Miyaura cross-coupling [a] of chloroarenes at room temperature. [12] This phosphabarrelene is a peculiar type of bulky phosphine ligand in that it is not electron donating but rather electron accepting, [13] which is bound to have a profound influence on the energetics of the elementary steps (OA, TM, and RE) of the catalytic process. Our goals here are manifold.…”