A cleavable linker strategy for optimising enolate alkylation reactions of a polymer-supported Evans' oxazolidin-2-one.
نویسندگان
چکیده
A cleavable linker strategy has been used to optimise the enolate alkylation reactions of a recyclable L-tyrosine derived polymer-supported oxazolidin-2-one for the asymmetric synthesis of a series of chiral alpha-alkyl acids.
منابع مشابه
Rhodium-catalyzed allylic substitution with an acyl anion equivalent: stereospecific construction of acyclic quaternary carbon stereogenic centers.
A highly regio- and stereospecific rhodium-catalyzed allylic alkylation of tertiary allylic alcohol derivatives with a cyanohydrin pronucleophile is described. This direct and operationally simple protocol provides a fundamentally novel approach toward the synthesis of α-quaternary substituted ketones and circumvents many of the inherent problems associated with conventional enolate alkylation ...
متن کاملSuperQuat 5,5-dimethyl-4-iso-propyloxazolidin-2-one as a mimic of Evans 4-tert-butyloxazolidin-2-one.
The incorporation of a gem-dimethyl group at the 5-position of a chiral oxazolidinone biases the conformation of the adjacent C(4)-stereodirecting group such that the gem-dimethyl-4-iso-propyl combination mimics a C(4)-tert-butyl group, providing higher levels of stereocontrol than a simple 4-iso-propyloxazolidinone. The generality of this principle is demonstrated with applications in stereose...
متن کاملEnolate Ions and Enols Halogenation Reactions Alkylation Reactions Condensation Reactions Enolate Ions from -Dicarbonyl Compounds Other Reactions of Enolate Ions and Enols
18.1 Enolate Ions and Enols We described in Chapters 13 and 16 that the C=O group of carbonyl compounds is reactive to attack by both nucleophiles (N:) and electrophiles (E+). We also saw in Chapter 13 that the C=O group causes Hs attached to its α-C (H-Cα-C=O) to be unusually acidic. As a result, these α-CH's are removed by bases giving enolate ions (-:Cα-C=O) Figure 18.01) that can react as n...
متن کاملNon-cross-linked polystyrene-supported 2-imidazolidinone chiral auxiliary: synthesis and application in asymmetric alkylation reactions
Asymmetric alkylation reactions using non-cross-linked polystyrene (NCPS)-supported 2-imidazolidinone chiral auxiliaries were successfully investigated with excellent diastereocontrol (>99% de). The recovery and the recycling of this soluble polymer-supported chiral auxiliary were achieved in order to produce highly optical pure carboxylic acids.
متن کاملCatalytic Enantioselective Alkylation of Prochiral Ketone Enolates
The synthesis of stereogenic all-carbon quaternary centers remains a formidable challenge, notwithstanding the strides made by modern organic chemistry in this regard [1]. Contemporary advances in enolate alkylation havemade it a fundamental strategy for the construction of C–C bonds [2]. Although methods for the reaction of a number of enolate types (e.g., ester, ketone, and propionimide) with...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Chemical communications
دوره 4 شماره
صفحات -
تاریخ انتشار 2008