157749-01-4Relevant articles and documents
Synthesis, structure, and reactivity of N-indolyl complexes of the chiral rhenium Lewis acid [(η5-C5H5)Re(NO)(PPh3)] +: Diastereoselective electrophilic additions
Johnson, Todd J.,Arif, Atta M.,Gladysz
, p. 3182 - 3193 (2008/10/08)
Reactions of the triflate complex (η5-C5H5)Re(NO)(PPh3)(OTf) (3) and indolide salts K(NCH=C(R)C=CCH=CHCH=CH) give the N-indolyl complexes (η5-C5H5)Re(NO)(PPh 3)-(NCH=C(R)C=CCH=CHCH=CH) (2, R = H/CH3/C2H5 (a/b/c); 71-59% after crystallization). Reactions of 2a,b and HOTf give the indolenine complexes [(η5-C5H5)Re(NO)(PPh 3)-(N=CHCH(R)C=CCH=CHCH=CH)]+ TfO- (4+TfO-; a, 93%; b, 77%, (86-92):(14-8) SR,RS/ SS,RR Re,C diastereomers). Reaction of 2b and CH3OTf gives [(η5-C5H5)Re(NO)(PPh 3)-(N=CHC(CH3)2C=CCH=CHCH=CH)] +TfO- (5+TfO-, 96%). Reactions of 2b and C2H5OTf, and 2c and CH3OTf, give [(η5-C5H5)Re(NO)(PPh 3)(N=CHC(CH3)(C2H 5)C=CCH=CHCH=CH)]+ TfO- (6+TfO-, 92-96%; 65:35, 17:83 SS,RR/SR,RS, respectively). Reaction of 2b and (η5-C5H5)Re(NO)(PPh3)(IC 2H5)]+BF4- gives 6+BF4- (93%, 91:9 SS,RR/SR,RS) and (η5-C5H5)Re(NO)(PPh3)(I) (84%). Reactions of 5+TfO- and CH3MgCl or LiB(C2H5)3H (THF, -80°C) give addition products (η5-C5H5)Re(NO)(PPh 3)(NCH(R)C(CH3)2C=CCH=CHCH=CH) (R = CH3 (95:5 SS,RR/SR,RS), H). The latter and HOTf yield indoline complex [(η5-C5H5)Re(NO)-(PPh 3)(HNCH2C(CH3)2C=CCH=CHCH=CH)] +TfO- (9+TfO-, 85%), which when treated with C≡NCH2Ts (60°C, CHCl3) gives 3,3-dimethylindoline (81%) and [η5-C5H5)Re(NO)-(PPh 3)(C≡NCH2Ts)]+TfO- (14+TfO-, 77%). Reaction of 3 and C≡NCH2Ts also gives 14+TfO- (94%), which is reduced by BH3·THF (THF, reflux) to (η5-C5H5)Re(NO)(PPh3)(CH 3) (60%). The crystal structure of 2c, reactions of nonracemic compounds, and rationales for the preceding configurational assignments are also reported.
