A new route to β-keto-δ-lactones: Practical preparation of (R)-3-hexyl-5,6-dihydro-4-hydroxy-6-undecyl-2H-pyran-2-one, a key intermediate in the asymmetric synthesis of tetrahydrolipstatin
作者:John J. Landi、Lisa M. Garofalo、Keith Ramig
DOI:10.1016/s0040-4039(00)60566-x
日期:1993.1
A formal asymmetric synthesis of the anti-obesity drug tetrahydrolipstatin is reported. The advanced intermediate (R)-3-hexyl-5, 6-dihydro-4-hydroxy-6-undexyl-2H-pyran-2-one is prepared in a brief sequence cyclization reaction. The sequence is also used to prepare other β-ketolactones.
A process for producing a biodegradable polymer, which comprises subjecting a cyclic compound of the following formula (1) or (2) to ring opening polymerization:
wherein R1 is a C1-1 o alkyl group,
wherein R2 is a C1-10 alkyl group, and R3 is a hydrogen atom or a C1-1 0 alkyl group.
Synthesis of 3,6-dialkyl-5,6-dihydro-4-hydroxy-pyran-2-one
申请人:Roche Colorado Corporation
公开号:US06545165B1
公开(公告)日:2003-04-08
The present invention relates to a novel process for producing a &dgr;-lactone of the formula:
using an acyl halide of the formula:
wherein R1, R2 R3 and X are described herein, as well as novel intermediates. In particular, the present invention relates to a process for enantioselectively producing the (R)-&dgr;-lactone.
Asymmetric Synthesis of 3,4,6-Trisubstituted 2,5-Diketopiperazines by Using Dynamic Kinetic Resolution of α-Bromo Tertiary Acetamides
作者:Jinho Baek、Seock Yong Kang、Chan Im、Yong Sun Park
DOI:10.1002/ejoc.201301936
日期:2014.5
A new and efficient method for the asymmetric synthesis of 3,4,6-trisubstituted 2,5-diketopiperazines has been developed. The dynamickineticresolution of L-amino-acid-derived α-bromo tertiary amides in the nucleophilicsubstitution reaction with p-anisidine and a subsequent deprotection-cyclization process provides rapid access to diverse cis-2,5-diketopiperazines 5a–5o and proline-containing trans-2
Influence of palladium(II) complexes on the cycloaddition of α-bromoalkyl ketenes to cyclopentadiene
作者:Ian J.S Fairlamb、Julia M Dickinson、Ileana M Cristea
DOI:10.1016/s0040-4020(01)00092-8
日期:2001.3
Palladium(II) complexes, of the type PdL2X2 and PdX2, influence both the yields and endo/exo ratio in formation of several 7-bromo-7-alkylbicyclo[3.2.0]hept-2-en-6-ones. Standard dehydrochlorination of α-bromoacyl chlorides with triethylamine in the presence of cyclopentadiene and palladium catalyst promotes the formation of the exo cycloadducts, which is accompanied by an improvement in the yields
PdL 2 X 2和PdX 2类型的钯(II)配合物会影响几种7-溴-7-烷基双环[3.2.0] hept-2-en-6-的形成中的收率和内/外比。那些。在环戊二烯和钯催化剂的存在下的三乙胺α-bromoacyl氯化物的标准脱氯化氢促进形成外cycloadducts,这是伴随着产率两者的改善内切和外切cycloadducts。讨论了钯介导的环加成反应的机理。