Chiral Diol Promoted Boronates Addi3on Reac3ons Lu Yan Morken Group Boston College
Main Idea R R B or R R B Ar * exchange B * * or B Ar R 1 R 1 R 2 R 1 R 2 Products not nucleophilic enough nucleophilic R 1 R 2 R 3 nucleophlic addition to different kinds of electrophiles such as... 1. Chiral diols generally have electron with- drawing groups, so as to make the boron center more electron deficient 2. Lone pair of oxygen atom cannot donate to boron vacant p orbitals because of the strain of the diols. 2
Research Groups Sco$ E. Schaus Boston University Chiral diols catalyzed asymmetric allylbora3on reac3ons Jonathan M. Goodman University of Cambridge chanis3c study and computa3onal models J. Michael Chong University of Waterloo Asymmetric Allylbora3on reac3ons of binaphthol- modified boronates 3
Contents Asymmetric Allylbora3on Reac3ons of Ketones Asymmetric Allylbora3on Reac3ons of Acyl Imines Asymmetric Petasis Reac3ons Asymmetric Conjugate Addi3on to Enones Asymmetric addi3on of chromene acetals 4
Asymmetric Allylbora3on of Ketones 5
Asymmetric Allylbora3on Reac3ons previous example R 1b toluene, 4A sieves -78 o C B 1b C 2 ipr C 2 ipr C 9 19 70% yield 82% ee 72% yield 87% ee 78% yield 71% ee 86% yield, 79% ee Roush, W.; Walts, A.; oong, L. J. Am. Chem. Soc. 1985, 107, 8186-8190. 6
Asymmetric Allylbora3on Reac3ons previous example R (R,R)-6 toluene, 4A sieves -78 o C B (R,R)-6 82% yield 95% ee 93% yield 97% ee 72% yield 94% ee Roush, W.; Grover, P. J. rg. Chem. 1995, 60, 3806-3813. 7
Asymmetric Allylbora3on Using Binol- Modified Boronates I MM MM 1) n-buli MM MM 2) I 2 I FS 2 CF 2 C 2 CuI CF 3 CF 3 MM MM Amberlyst 15 C 3 /TF CF 3 CF 3 CF 3 CF 3 B B R CF 3 CF 3 Chong, J. rg. Le4. 2004, 6, 2701-2704. 8
Asymmetric Allylbora3on Using Binol- Modified Boronates aldehyde yield er 90 98:2 R 5j TF, -78 o C 1h R 93 97:3 93 97:3 CF 3 Cl B 5j 2 96 96:4 CF 3 94 97:3 F 3 C 98 88:12 90 88:12 Chong, J. rganic Le4ers 2004, 6, 2701-2704. 9
Asymmetric Allylbora3on Using Binol- Modified Boronates Ketone yield er 88 96:4 5j TF, -78 o C R' C 2 Br 87 97:3 R R' 48h CF 3 CF 3 B R 5j Cl 95 99:1 94 99:1 91 88:!2 75 95:5 98 75:25 Chong, J. rganic Le4ers 2004, 6, 2701-2704. 10
Asymmetric Allylbora3on Using Binol- Modified Boronates Chong, J. rganic Le4ers 2004, 6, 2701-2704. 11
Asymmetric Allybora3on of Ketones Catalyzed by Binol Deriva3ves ketones yield er R 1 R 2 + -i-pr B -i-pr 15% catalyst C 3 :CF 3 =1:3-35 o C R 1 R 2 Br 83 97:3 81 95.5:4.5 Br Br F 3 C 86 99.5:0.5 89 95.5:4.5 Br 83 99.5:0.5 81 96.5:3.5 S 88 97:3 Schaus, S. J. Am. Chem. Soc. 2006, 128, 12660-12661. S 88 97:3 12
Asymmetric Allybora3on of Ketones Catalyzed by Binol Deriva3ves ketones yield er 83 97.5:2.5 R 1 R 2 + -i-pr B -i-pr 15% catalyst C 3 :CF 3 =1:3-35 o C R 1 R 2 Cl 76 98:2 Br 88 96.5:3.5 87 97.5:2.5 Br 83 96:4 91 96.5:3.5 93 95:5 Schaus, S. J. Am. Chem. Soc. 2006, 128, 12660-12661 13
Asymmetric Propargyla3on of Ketones using Allenyl boronates Br R 1 + B R 2 10% catalyst microwave, neat R 1 R 2 Br Schaus, S. rganic Le4ers, 2011, 13, 4020-4023. 14
Ketone yield er Ketone yield er Cl Cl TBDPS 85 97:3 87 98:2 85 99:1 96 98:2 97 99:1 98 98:2 86 97:3 91 95:5 96 90:10 2 F 3 C S S 91 95:5 83 96:4 88 97:3 87 98:2 88 97:3 83 96:4 85 96:4 Br Br 86 79:21 88 96:4 83 97:3 68 96:4 93 90:10 60 97:3 15
Asymmetric Allybora3on of Ketones chanis3c Study -i-pr B -i-pr ipr K RDS ipr ipr B ipr B ipr B Schaus, S. Angew. Chem. Int. Ed. 2009, 48, 8679-8682. 16
Asymmetric Allybora3on of Ketones chanis3c Study ketone yield e.r 96 99:1 R 1 R 2 + B (S)-1, 2 mol% tbu RT, 24h Br R 2 R 1 2 Br F 88 99:1 93 99:1 97 99:1 95 99:1 Br Br 95 98:2 S 93 >99:1 92 99:1 Schaus, S. Angew. Chem. Int. Ed. 2009, 48, 8679-8682. S 17
Asymmetric Allybora3on of Ketones chanis3c Study ketones yield er C 3 95 98:2 97 99:1 95 99:1 96 98:2 + C 3 + C 3 B (S)-1, 4% tbu RT, 24h 94% yield 97:3 e.r. 98:2 d.r. (S)-1, 4% B tbu RT, 24h 96% yield 99:1 e.r. 97:3 d.r. 3 C 3 C C 3 C 3 Et 98 99:1 98 >99:1 93 99:1 Cl 95 >99:1 Schaus, S. Angew. Chem. Int. Ed. 2009, 48, 8679-8682. 18
Asymmetric Allybora3on of Ketones Computa3onal model * -i-pr B -i-pr ipr K RDS ipr * B * B * B Goodman, J. rganic Le4ers 2009, 11, 37-40. 19
Asymmetric Allybora3on of Ketones Computa3onal model Goodman, J. rganic Le4ers 2009, 11, 37-40. 20
Asymmetric Allybora3on of Ketones Computa3onal model Goodman, J. rganic Le4ers 2009, 11, 37-40. 21
Asymmetric Allylbora3on of Acyl Imines Asymmetric Petasis Reac3ons 22
Asymmetric Synthesis of Propargylamides -Acetylimines yield ee C 3 75 92 R C 3 2f C 2 Cl 2, -78 o C to rt, 24h C 3 R C 6 13 Cl C 3 C 3 72 91 81 92 B C 6 13 2f C 3 C 3 76 92 78 99 C 3 70 >99 Chong, J. rganic Le4ers 2006, 8, 15-18. C 3 75 67 23
Asymmetric Synthesis of Propargylamides TBS 1) LiMDS, TMSCl 2) AcCl, CCl 3 3) B TBS Ac Ac (-)--acetylcolchinol 6 anti-tumor activity Chong, J. rganic Le4ers 2006, 8, 15-18. 24
Asymmetric Allylbora3on of Cyclic Imines imine yield ee 92 95 R 1 R 2 2h toluene, -78 o C to r.t. 24h R 1 R 2 78 98 86 98 CF 3 Cl 88 95 Cl CF 3 B 2 90 99 CF 3 80 94 2h CF 3 84 94 Ts 65 91 Chong, J. J. Am. Chem. Soc. 2006, 128, 9646-9647 71 92 25
Asymmetric Allylbora3on of Cyclic Imines Selec3vity Model Chong, J. J. Am. Chem. Soc. 2006, 128, 9646-9647 26
Asymmetric Allylbora3on of Acyl Imines -ipr ipr- B + R 2 R 1 R 2 15% 7h 3A MS toluene,rt R 2 Schaus, S. J. Am. Chem. Soc. 2007, 129, 15398-15404. 27
Asymmetric Allylbora3on of Acyl Imines -ipr ipr- B + R 15% 7h 3A MS toluene,rt R Br F 87% yield 99:1 er 83% yield 98:2 er 86% yield 97.5:2.5 er 85% yield 95:5 er 94% yield 98:2 er F CF 3 S 91% yield 95.5:4.5 er 89% yield 97.5:2.5 er 83% yield 96:4 er 81% yield 95:5 er 88% yield 96:4 er 83% yield 99.5:0.5 er 82% yield 95.5:4.5 er 80% yield 98:2 er 81% yield 99.5:0.5 er 82% yield 95.5:4.5 28
Asymmetric Allylbora3on of Acyl Imines -ipr ipr- B + R 15% 7h 3A MS toluene,rt R C 3 tbu 13% yield 57:43 er 25% yield 65:35 er 41% yield 65:35 er 52% yield 70:30 er 82% yield 95:5 er 3 C C 3 C 3 Br F 76% yield 97:3 er 80% yield 97.5:2.5 er 83% yield 96.5:3.5 er 84% yield 97.5:2.5 83% yield 97:3 er 29
Asymmetric Allylbora3on of Acyl Imines mechanis3c study Schaus, S. J. Am. Chem. Soc. 2007, 129, 15398-15404. 30
Asymmetric Allylbora3on of Acyl Imines F F 1) xalyl chloride DMF, C 2 Cl 2 F F -ipr B -ipr 15mol% R-7h F F 2) TMS 3A MS toluene, rt F F 75% yield, 91% ee Maraviroc anti-iv Schaus, S. J. Am. Chem. Soc. 2007, 129, 15398-15404. 31
Asymmetric Allylbora3on of Acyl Imines Ar nbu B nbu + R 3 (S)-4b, 15% R 2 toluene 0 o C to RT R 3 Ar R 2 R 3 R 3 nbu (S)-4b, 15% B + R 1 nbu toluene R 2 0 o R R C to RT 1 2 Br Br R 3 nbu (S)-4b, 15% B + nbu toluene R R 2 0 o 1 C to RT R 1 R 3 R 2 Schaus, S. Angew. Chem. Int. Ed. 2009, 48, 4337-4340. 32
boronate imines yield er Boronate imines yield e.r. nbu B nbu 85 97.5:2.5 nbu B nbu 80 98:2 F S nbu B nbu nbu B nbu nbu B nbu nbu B nbu 88 99:1 82 96.5:3.5 83 96:4 75 98:2 nbu B nbu nbu B nbu nbu B nbu Br Br nbu B nbu 82 98:2 91 96:4 95 99:1 72 97:3 nbu B nbu 80 95.5:4.5 nbu B nbu Cl 98 98:2 nbu B nbu nbu B nbu S Br 91 95:5 75 98:2 nbu B nbu nbu B nbu S Br 80 98.5:1.5 89 96:4 33
R 3 R 3 nbu (S)-4b, 15% B + nbu toluene R 2 0 o R R C to RT 2 1 R 1 boronates imines yield er nbu B nbu nbu B nbu 99 96:4 76 93:7 F nbu B nbu 72 94:6 S C 6 13 nbu B nbu 90 92:8 nbu B nbu 71 97:3 nbu B nbu 80 96:4 34
Asymmetric Petasis Reac3ons amine yield er Et B Et 15% 5j R 1 R 2 R 1 R + 2 + C 2 Et 3A MS, -15 o C toluene C 2 Et Bn Bn tbu 81 95:5 73 93:7 Bn 82 97:3 Bn C 80 98.5:1.5 Bn C 2 Et 94 95:5 Bn TMS 84 95:5 Bn 74 89:11 87 97:3 Schaus, S. J. Am. Chem. Soc. 2008, 130, 6922-6923. 35
Asymmetric Petasis Reac3ons boronate yield er Et B Et Et B Et 81 95.5:4.5 84 96:4 R 1 R 2 Et B Et + Bn 2 + C 2 Et 15% 5j 3A MS, -15 o C toluene R 1 R 2 Bn 2 C 2 Et Br F Et B Et Et B Et 82 95:5 80 95:5 F 3 C Et B Et 82 95:5 S Et B Et 87 95:5 Et B Et 76 97:3 n-bu Et B Et 73 95:5 Schaus, S. J. Am. Chem. Soc. 2008, 130, 6922-6923. n-bu Et B Et Et B Et 78 95:5 71 93:7 36
Asymmetric Conjugate Addi3on of Enone 37
Asymmetric Conjugate Addi3on First Example 1) R B R 2) 2 Substrate Scope 96% 100% 70% 70% Brown,. J. Am. Chem. Soc. 1977, 99, 954-956. 38
Asymmetric Conjugate Addi3on of alkynylboronates to enones enones yield %ee R' R'' reagent 2, C 2 Cl 2 room temp R' C 6 13 R'' 88 85 50 85 85 41 B C 6 13 C 6 13 80 16 82 74 91 98 91 95 Br Br 93 75 Chong, J. J. Am. Chem. Soc. 2000, 122, 1822-1823. 39
Asymmetric Conjugate Addi3on enones R yield% %ee 20% Catalyst n-c 6 13 94 86 i-pr- R B i-pr- R n-c 6 13 93 96 R' R'' C 2 Cl 2,room temp R' R'' n-c 6 13 78 88 I n-c 6 13 89 94 95 82 I 97 90 C 2 Bn 91 86 C 2 Bn 94 95 Chong, J. J. Am. Chem. Soc. 2005, 127, 3244-3245. 40
Asymmetric Conjugate Addi3on chanism i-pr- B i-pr- R * ipr * B R R -i-pr B -i-pr R * B i-pr- B i-pr- R Chong, J. J. Am. Chem. Soc. 2005, 127, 3244-3245. 41
Asymmetric Conjugate Addi3on chanism Goodman, J. J. Am. Chem. Soc. 2006, 128, 3116-3117. 42
Asymmetric Allylbora3on of Chromene Acetals 43
Asymmetric Addi3on to Chromene Acetals Bn Bn Et R + Et B R 1 1 R Ce(Tf) Et 3 4 EtAc R 2 R 2 R 3 R 1 Et Et Et + Et B R 2 tartaric acid 5 20% R 1 R 2 Cl 3 C 2 (20 equiv) Et MPA or MP 5 Schaus, S. Angew. Chem. Int. Ed. 2010, 49, 7096-7100. Schaus, S. rganic Le4ers 2011, 13, 6316-6319. 44
Asymmetric Addi3on to Chrome Acetals Bn Bn Et R + Et B R 1 1 R Ce(Tf) Et 3 4 EtAc R 2 R 2 R 3 CF 3 5 4 o C 71% y 96.5:3.5 er -40 o C, 1eq tbu 71% y 98.5:1.5 er -20 o C, 75% y 99:1 er 2 S -40 o C, 1 eq tbu 77% y 99.5:0.5 er 10 o C, 59% y 93:7er -20 o C, 74% y 96:4 er 4 o C, 40% y 96:4 er 4 o C, 50% y 97.5:2.5 er 45
R 1 Et Et Et + Et B R 2 tartaric acid 5 20% R 1 R 2 Cl 3 C 2 (20 equiv) Et MPA or MP 5 Cl 2 Et MP, -10 o C 81%y, 94:6 er Et MP, -20 o C 74%y, 94:6 er Et MPA, 4 o C 89%y, 95:5 er Et MPA, 4 o C 73%y, 92:8 er Et MPA, -10 o C 87%y, 94:6 er Et Cl MPA, -10 o C 86%y, 92:8 er Et MPA, 4 o C 77%y, 95:5 er F Et MPA, -10 o C 83%y, 96:4 er S Cl Et MPA, -20 o C 82%y, 95:5 er Et MP, -20 o C 81%y, 92:8 er Et F MP, 4 o C 73%y, 88:12 er 46
Asymmetric Addi3on to Chrome Acetals Proposed chanism Bn Bn Et Et B 2Et Bn Bn M B Et Bn Bn B + M Et Schaus, S. Angew. Chem. Int. Ed. 2010, 49, 7096-7100. 47
Summary 3,3- disubs3tuted BILs can catalyze asymmetric allylbora3on, alkynyl bora3on, allenylbora3on, reac3ons of different nucleophiles Yet, many of the men3oned reac3ons can only work well on aroma3c substrates. Develop other diol catalyze asymmetric process such as hydrobora3on, conjugate reduc3ons seems promising. 48