61550-03-6

Upstream product

• 75-77-4 chloro-trimethyl-silane 
• 22122-36-7 3-methyl-5H-furan-2-one 
• 616-02-4 citraconic acid anhydride 
• 27607-77-8 trimethylsilyl trifluoromethanesulfonate 
• 1679-47-6 3-methyltetrahydro-2-furanone 

Downstream Products

• 1092582-40-5 C₁₃H₁₃NO₄ 
• 84519-63-1 (R,E)-4-phenyl-3-buten-2-yl acetate 
• 74457-38-8 (E)‐4‐phenylbut‐3‐en‐2‐yl acetate 
• 1602489-93-9 diethyl (S)-hydroxy[(2R)-4-methyl-5-oxo-2,5-dihydrofuran-2-yl]phenylmethylphosphonate 

Relevant academic research and scientific papers

Umpolung of hemiaminals: Titanocene-catalyzed dehydroxylative radical coupling reactions with activated alkenes

Radical measures: A radical coupling reaction, which is proposed to proceed through in situ chlorination of a hydroxy group by Me3SiCl, is used to form quaternary carbon centers with amino groups in α position. The reaction can be scaled up and

Total synthesis of (+)-azaspiracid-1. An exhibition of the intricacies of complex molecule synthesis

The synthesis of the marine neurotoxin azaspiracid-1 has been accomplished. The individual fragments were synthesized by catalytic enantioselective processes: A hetero-Diels-Alder reaction to afford the E- and HI-ring fragments, a carbonyl-ene reaction to furnish the CD-ring fragment, and a Mukaiyama aldol reaction to deliver the FG-ring fragment. The subsequent fragment couplings were accomplished by aldol and sulfone anion methodologies. All ketalization events to form the nonacyclic target were accomplished under equilibrating conditions utilizing the imbedded configurations of the molecule to adopt one favored conformation. A final fragment coupling of the anomeric EFGHI-sulfone anion to the ABCD-aldehyde completed the convergent synthesis of (+)-azaspiracid-1.

Stereoselective synthesis of freelingyne and related γ-alkylidenebutenolides via vinylogous Mukaiyama aldol additions

Following the strategy of Scheme 1, a Mukaiyama aldol addition/anti-elimination route to stereopure γ-alkylidenebutenolides 4 was established. The addition giving 27 was only moderately diastereoselective but the products lk- and ul-27 were chromatographically separable (Scheme 4). They underwent highly selective anti-eliminations in the presence of triflic anhydride-pyridine or Burgess' reagent, furnishing the thiophene-containing butenolides Z- and E-28, respectively (Scheme 5). The Mukaiyama aldol addition leading to compound 29 was 100% lk-selective when mediated by BF3 etherate and 87 : 13 ul-selective in the presence of ZnBr2 (Scheme 6). Stephens-Castro couplings of the resulting butenolides lk- and ul-29 with 3-ethynylfuran proceeded with complete conservation of the stereochemical integrity (Scheme 7). The subsequent anti-eliminations of water were best realized by treatment with DEAD-PPh3. They provided freelingyne (Z-9) with ds = 92 : 8 and its isomer E-9 with ds = 98 : 2 (Scheme 8). Analogously, the differently substituted (trimethylsiloxy)furans 15 or 16 provided the freelingyne analogs Z-10, E-10 and Z-11 (Schemes 6-8).