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4 5 4_ B_ LDA then A_ TMEDA 5_ D_ catecholborane 1_2_3 1_ NaN

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4 5 4_ B_ LDA then A_ TMEDA 5_ D_ catecholborane 1_2_3 1_ NaN Powered By Docstoc
					                                    Denksport: Cruentaren A by A. Fürstner
                    A. Fürstner, M. Bindl, L. Jean, Angew. Chem. Int. Ed. 2007, 46, 9275-9278


    O       O

O       N

        Bn
                                                    I
            1,2,3                   1) NaN(SiMe3)2,
                                    2) EtOH, Ti(OEt)4
                                    3) (MeO)(Me)NH•HCl



                       A


            4                       4) B, LDA
                                                           MeO O                Estimate the pKA of the most acidic hydrogen
                                       then A, TMEDA
                                                                    O           in structure B
                                                       MeO              SiMe3
                                                              B




                                                                   H PhPh
                               C                                        O       Name this reaction and provide a mechanism,
                                                                    N B
                                                                                showing a 3D drawing that explains the
            5                       5) D, catecholborane          D    Bu       stereochemical outcome
                                 E
                                     6) TBDPSOTf, 2,6-lutidine
                  6, 7, 8            7) tris(dimethylamino)-sulfonium
                                        difluorotrimethylsilicate
                                     8) 2,4,6-trifluoro-1,3,5-triazine, py


      MeO         O

                      F

MeO

  TBDPSO


                                 F


          O       O

      O       N

 G            Bn
                                                       I          OTHP
                                     9) NaN(SiMe3)2,
                                     10) LiBH4
                  8, 9, 10, 11       11) Lindlar cat. H2
                                     12) DMP
             H
                                                        Name this aldol reaction and provide a 3D
                                                        transition state to explain the stereochemical
13, 14, 15, 16       13) G, Et2BOTf, DIPEA              outcome
                     14) TBSOTf, 2,6-lutidine
                     15) LiBH4
                     16) DMP




             I
                           Me3Si
                                                        Name this propargylation and provide a 3D
                                      B
17                   17)                   J            transition state to explain the stereochemical
                                                        outcome




                                                Soderquist
                                                propargylation


                 K


18, 19, 20           18) TESCl, im
                     19) n-BuLi,MeI
                     20) HF•py, py
                     L


   F+L
                                                               N
                         21) NaN(SiMe3)2                N Mo
       21, 22            22) M (10 mol%)                       N

                                                         M




                                                    O    OTBS
                                               HO
                                                         O

                                                                                      HO
                         N                                                        O

       23, 24, 25,       23) Lindlar cat, H2                                      NH
       26, 27, 28,       24) MgBr2•Et2O                                 HO
       29                25) [Zn(N3)2•py2], PPh3, DIAD
                                                                   OH
                         26) PPh3                                        O
                         27) O, HBTU, HOAt, DIPEA
                         28) BCl3                                            O   cruentaren A
                         29) HF aq.                       HO
cruentaren A
                                                                        HO

				
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posted:12/14/2013
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