噻唑烷并手性口恶唑硼烷催化剂 结构和性质的量子化学研究
Quantum Chemical Study on Structures and Properties of Chiral Thiazolidino ［3,4-c］ Oxazaborolidine Catalyst
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摘要: 采用量子化学从头计算方法研究了噻唑烷并手性口恶唑硼烷催化剂及其硼烷加合物的结构和性质.选用Hartree-Fock方法在6-31g基组下进行了全优化计算，并计算了催化剂及其加合物的红外振动光谱.催化剂具有扭曲的椅式构型，与硼烷在N原子处配位形成加合物，反应是放热的.加合物的形成，一方面使得催化剂上B原子所带正电荷增加，有利于与酮羰基氧的配位反应进行；另一方面使得BH3中B-H键被削弱，有利于后继反应中H 从BH3到酮羰基碳的转移，从而增强了催化反应的活性.
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关键词:
- 从头计算 /
- 噻唑烷并手性口恶唑硼烷 /
- 不对称催化还原 /
- 催化剂-硼烷加合物
Abstract: The ab initio molecular orbital method is employed to s tudy the structures and properties of chiral thiazolidino ［3,4-c］ oxazaboroli dine, as a catalyst, and its borane adduct. All the structures are optimized com pletely at the HF/6-31g level and their IR vibrational spectra computed. The ca talyst is a twisted chair structure and reacts with borane at the N site of the catalyst to form catalyst-borane adduct. The formation reaction is exothermic. The formation of the catalyst-borane adduct causes the BBH3—HBH3 bond of the BH3 moiety to be weakened, which is of great advantage to the h ydri de transfer from the BH3 moiety to the carbonyl carbon of ketone, and the posi tive charges of boron in the catalyst moiety to be increased, which makes the re action between the carbonyl oxygen of ketone and the boron of the catalyst easie r. -
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