330652-59-0

Upstream product

• 56017-85-7 (S)-4-ethynyl-2,2-dimethyl-1,3-dioxolane 
• 130874-89-4 (2R,3R)-1,4-dimethoxy-1,1,4,4-tetraphenyl-2,3-butandiol 
• 15186-48-8 2,3-isopropylidene-glyceraldehyde 
• 56017-84-6 4-(2,2-Dibromoethenyl)-2,2-dimethyl-1,3-dioxolane 
• 220156-18-3 (4R,5R)-4,5-Bis-(methoxy-diphenyl-methyl)-[1,3,2]dioxaborolane 

Relevant academic research and scientific papers

Enantiomerically pure cyclopropylboronic esters: Auxiliary- versus substrate-control

Stable, enantiomerically pure cyclopropylboronic esters are synthesized from alkynes by a hydroboration-cyclopropanation sequence. The direct hydroboration - utilizing 1,3,2-dioxaborolane 4 - is most convenient, however, with more functionalized side-chains it failed to give the desired intermediates. Using the more reactive dicyclohexylborane, followed by oxidation and transesterification, is a good alternative one-pot conversion. Cyclopropanations were performed either following a Simmons-Smith protocol or with diazomethane-palladium(II) acetate. The influence on the diastereoselectivity of the auxiliary 1 is compared with the influence of an additional stereogenic center in the side-chain. The Royal Society of Chemistry 2000.