Diastereodivergent synthesis of trisubstituted alkenes through protodeboronation of allylic boronic esters: application to the synthesis of the Californian red scale beetle pheromone.
نویسندگان
چکیده
E-allylic boronic esters undergo a highly diastereoselective protodeboronation with TBAF⋅3 H(2)O to give Z-trisubstituted alkenes. The selectivity can be switched to give predominantly the E-alkene instead by using KHF(2)/TsOH (see scheme). The utility of the methodology has been illustrated in a short synthesis of a component of the sex pheromone of the Californian red scale beetle.
منابع مشابه
Stereocontrolled synthesis of 1,5-stereogenic centers through three-carbon homologation of boronic esters.
Allylic pinacol boronic esters are stable toward 1,3-borotropic rearrangement. We developed a Pd(II)-mediated isomerization process that gives di- or trisubstituted allylic boronic esters with high E selectivity. The combination of this method with lithiation-borylation enables the synthesis of carbon chains that bear 1,5-stereogenic centers. The utility of this method has been demonstrated in ...
متن کاملHighly selective allylborations of aldehydes using α,α-disubstituted allylic pinacol boronic esters.
α,α-Disubstituted allylic pinacol boronic esters undergo highly selective allylborations of aldehydes to give tetrasubstituted homoallylic alcohols with exceptional levels of anti-Z-selectivity (>20:1). The scope of the reaction includes both acyclic and cyclic allylic boronic esters which lead to acyclic and exocyclic tetrasubstituted homoallylic alcohols. The use of β-borylated allylic boroni...
متن کاملProtodeboronation of tertiary boronic esters: asymmetric synthesis of tertiary alkyl stereogenic centers.
While tertiary boranes undergo efficient protodeboronation with carboxylic acids, tertiary boronic esters do not. Instead, we have discovered that CsF with 1.1 equiv of H2O (on tertiary diarylalkyl boronic esters) or TBAF·3H2O (on tertiary aryldialkyl boronic esters) effect highly efficient protodeboronation of tertiary boronic esters with essentially complete retention of configuration. Furthe...
متن کاملSynthesis of enantioenriched tertiary boronic esters from secondary allylic carbamates. Application to the synthesis of C30 botryococcene.
Enantioenriched secondary allylic carbamates have been deprotonated with sBuLi and reacted with boronic esters. In contrast to other electrophiles, high α-selectivity was observed and the boronate complexes were formed with almost complete retention of stereochemistry. The boronate complexes underwent a stereospecific 1,2-migration leading to tertiary allylic boronic esters with high er (>98:2)...
متن کاملEnantioselective installation of adjacent tertiary benzylic stereocentres using lithiation–borylation–protodeboronation methodology. Application to the synthesis of bifluranol and fluorohexestrol† †Electronic supplementary information (ESI) available: Detailed experimental procedures and spectroscopic data for all new compounds. X-Ray data analysis for compound 2. See DOI: 10.1039/c4sc03901g
1,2-Diaryl ethanes bearing 1,2-stereogenic centres show interesting biological activity but their stereocontrolled synthesis has not been reported forcing a reliance of methods involving diastereomer and enantiomer separation. We have found that this class of molecules can be prepared with very high stereocontrol using lithiation–borylation methodology. The reaction of an enantioenriched benzyl...
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:
- Angewandte Chemie
دوره 51 50 شماره
صفحات -
تاریخ انتشار 2012