2-烯基苯酚和烯酰胺的催化对映选择性卤环化已经通过使用手性酰胺磷酸盐催化剂和卤代路易斯酸实现。密度泛函理论计算表明催化剂的路易斯碱度在反应性和对映选择性中起重要作用。所得手性卤代色满可以在短时间内转化为 α-生育酚、α-生育三烯酚、代达林 A 和英格列酮。此外,具有不饱和侧链的卤化产物可在自由基环化条件下提供多环加合物。
Abstract The synthesis of 1,1‐dimethyl‐4‐indanols (3a,b) has been achieved by intramolecular Friedel–Crafts cyclization of 2‐(3‐methyl‐2‐butenyl)phenols (5a,b) or 1‐methoxy‐2‐(3‐methyl‐2‐butenyl)benzenes (6a,b) followed by demethylation, respectively.It was found that the solvent was critical for the formation of different products in the intramolecular Friedel–Crafts reactions of 6. The unexpected
The ene reaction of singletoxygen with prenylated dihydroxyacetophenones led to the 2-hydroperoxy-3-methylbut-3-enyl derivatives as the major product. This original regioselectivity outlined a new effect, in competition with the previously established large group non-bonding effect. The oxidation products distribution could be explained by a stabilising interaction between the phenolic hydrogen, ortho
Catalytic Asymmetric Prins Cyclizations: Cation Generation and Trapping with (BINAP)Pt Dications
作者:Charles A. Mullen、Michel R. Gagné
DOI:10.1021/ol052845r
日期:2006.2.1
(R)-[(to vertical bar B vertical bar NAP)Pt(NC6F5)(2)][SbF6](2) (5) catalyzes the highly enantioselective Prins reaction between 2-allylphenols and glyoxylate esters. Other Lewis acid catalysts favor glyoxylate-ene products.
ortho-Prenylphenol photooxygenation as a straightforward access to ortho-(2-hydroxy-3-methylbut-3-enyl)phenols
Photooxygenation (O-1(2)) Of ortho-prenylphenols followed by a reduction (PPh3) at low temperature (-30 degrees C) yields a mixture of ortho-(2-hydroxy-3-methylbut-3-enyl)phenols and ortho-(3-hydroxy-3-methyl-but-1-enyl)phenols. However, by running the two-step sequence at a higher temperature (15 degrees C), the secondary allylic alcohol could be selectively recovered. (C) 2000 Elsevier Science Ltd. All rights reserved.