Molecular Complexity via C–H Activation: A Dehydrogenative Diels–Alder Reaction
摘要:
Traditionally, C-H oxidation reactions install oxidized functionality onto a preformed molecular skeleton, resulting in a local molecular change. The use of C H activation chemistry to construct complex molecular scaffolds is a new area with tremendous potential in synthesis. We report a Pd(II)/bis-sulfoxide-catalyzed dehydrogenative Diels-Alder reaction that converts simple terminal olefins into complex cycloadducts in a single operation.
Intramolecular Diels–Alder reactions using chiral ruthenium Lewis acids and application in the total synthesis of ent-ledol
作者:Sirinporn Thamapipol、E. Peter Kündig
DOI:10.1039/c1ob06121f
日期:——
ligand BIPHOP-F and a Cp or an indenyl ‘roof’ can efficiently catalyze asymmetric intramolecular Diels–Alder reactions of trienes to form bicyclic adducts with good to excellent asymmetric induction. This reaction forms the key step in a totalsynthesis of ent-ledol in 96% ee. The synthesis also helps to clarify the stereochemical assignment of ledol and inconsistencies in the measured optical rotation
Regioselective Alkylation of the Polyfunctional Nucleophile 1-(Methylthio)-3-triethylsilyloxypentadienyllithium
作者:Wolfgang Oppolzer、Roger L. Snowden、Paul H. Briner
DOI:10.1002/hlca.19810640706
日期:1981.11.4
γ-Selective sulfenylation of the triethysilyloxypentadienyllithium 1 gave the versatile alkylthiodene 4 which on successive deprotonation and alkylation furnished with high regioselectivity the γ-products 6. Fluoride-promoted silylether cleavage 6 7 may be followed by intramolecular [4 + 2]-addition 7c 8 and sulfoxide elimination 8 9. The conversions 7b 12 and 7a 17 demonstrate the feasibility of 5
Cyclobutanone-based tandem free radical rearrangements: Formation of bicyclic and tricyclic ketones
作者:Paul Dowd、Wei Zhang、Khalid Mahmood
DOI:10.1016/0040-4020(94)00961-s
日期:1995.1
Free radical reaction of endo-bromopropylbicyclo[4.2.0]oct-2-en-7-one 1 leads to deep-seated rearrangement and formation of the bridged tricyclic ketone 2. An authentic sample of 2 was prepared. Reaction of endobromoethylbicyclo[4.2.0]oct-2-en-7-one 18 generates an analogous bridged tricyclic ketone 20 together with cis-bicyclo[4.4.0]decenone 22. Experiments using Bu3SnD were carried out to explore
A cyclobutanone-based tandem free radical rearrangement
作者:Paul Dowd、Wei Zhang、Khalid Mahmood
DOI:10.1016/s0040-4039(00)77247-9
日期:1994.8
Freeradical reaction of endo-haloalkylbicyclo[4.2.0]oct-2-en-7-ones 1 and 11 leads to sequential rearrangement and formation of the novel, bridged tricyclic ketones 2 and 13. A mechanism for this unusual transformation is proposed.
3-Triethylsilyloxypentadienyllithium, a Versatile 1,3-Diene- or Vinyl Ketone-Building Block
作者:Wolfgang Oppolzer、Roger L. Snowden、Dana P. Simmons
DOI:10.1002/hlca.19810640705
日期:1981.11.4
(Table 1) aldehydes and ketones attack preferentially the γ-position of 4(Table 2). The desired γ-products 6 may be directly subjected to inter- and intramolecular [4 + 2]-additions as demonstrated by the reactions 5a ( 6d) 7 and 6h 19(Schemes 4 and 12). Alternatively, smooth fluoride-promoted silylether-cleavage 6 11(Scheme 8) provides a convenient approach to substituted vinyl ketones such as to