%0 Journal Article
%A Casey, Charles P.
%A Martins, Susie C.
%A Fagan, Maureen A.
%D 2004
%T Reversal of Enantioselectivity in the Hydroformylation of Styrene
with [2S,4S-BDPP]Pt(SnCl3)Cl at High Temperature Arises
from a Change in the Enantioselective-Determining Step
%U https://acs.figshare.com/articles/journal_contribution/Reversal_of_Enantioselectivity_in_the_Hydroformylation_of_Styrene_with_2_i_S_i_4_i_S_i_BDPP_Pt_SnCl_sub_3_sub_Cl_at_High_Temperature_Arises_from_a_Change_in_the_Enantioselective_Determining_Step/3340516
%R 10.1021/ja0318479.s002
%2 https://acs.figshare.com/ndownloader/files/5179729
%K BDPP
%K platinum hydride addition
%K formyl group
%K ee
%K High Temperature Arises
%K phenylpropanal
%K terminal
%K styrene
%K CO
%K TOF
%K aldehyde carbonyl
%K deuterium
%X Deuterioformylation of styrene catalyzed by [(2S,4S)-BDPP]Pt(SnCl3)Cl at 39 °C gave 3-phenylpropanal (3) and 2-phenylpropanal (2) (n:i = 1.8, 71% ee (S)-2) with deuterium only β to the aldehyde
carbonyl and in the formyl group. Small amounts of deuterium were also found in the internal (2.8%), cis
terminal (1.4%), and trans terminal (1.3%) vinyl positions of the recovered styrene. Deuterioformylation of
styrene at 98 °C gave 3- (3) and 2-phenylpropanal (2) (n:i = 2.3, 10% ee (R)-2) with deuterium both α and
β to the aldehyde carbonyl and in the formyl group. Deuterium was also found in the internal (20%), cis
terminal (12%), and trans terminal (12%) vinyl positions of the recovered styrene. These deuterioformylation
results establish that platinum hydride addition to styrene is largely irreversible at 39 °C but reversible at
98 °C. Hydroformylation of (E)- and (Z)-β-deuteriostyrene at 40 °C, followed by oxidation of the aldehydes
to acids, and subsequent derivitization to the (S)-mandelate esters confirmed that 84% of 2-phenylpropanal
(2) arises from platinum hydride addition to the si-face of styrene, while 73% of 3-phenylpropanal (3) arises
from platinum hydride addition to the re-face of styrene. At 100 °C, the effect of variable H2 and CO pressure
on n:i, % ee, and TOF of hydroformylation of styrene was investigated. The results are consistent with
enantioselectivity not being fully determined until the final hydrogenolysis of a platinum acyl intermediate.
%I ACS Publications