Bis‐Sulfamyl Imines: Potent Substrates for Asymmetric Additions of Arylboroxines under Rhodium Catalysis

Crampton, Rosemary H.; Woodward, Simon; Fox, Martin E.

doi:10.1002/adsc.201000838

Cited by 30 publications

(25 citation statements)

References 26 publications

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“…The asymmetric synthesis of enantioenriched 2‐methylbenzhydrylamine ( 2 ) has been reported in the phenylboroxine addition and hydrogenation of the corresponding imine. As shown in Scheme , we found that the rac ‐imine 6 i formed from furfural ( 3 i ) crystallizes in the conglomerate.…”

Section: Resultsmentioning

confidence: 95%

Highly Stereoselective Strecker Synthesis Induced by a Slight Modification of Benzhydrylamine from Achiral to Chiral

Takamatsu

Aiba

Yamada

et al. 2017

Chemistry A European J

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2-Methylbenzhydrylamine is a chiral variant of achiral benzhydrylamine; however, the chirality formed from the small difference between the phenyl and o-tolyl groups is not expected to induce sufficient stereoselectivity in conventional homogeneous reactions. Initiated by the spontaneous formation and asymmetric amplification of the enantioenriched N-benzhydryl-α-aminonitrile forming conglomerate, we here report that (S)- and (R)-configured title amine, upon the Strecker reaction with achiral aldehydes and HCN, afford the corresponding α-aminonitriles with up to >99.5 % diastereomeric excess, in conjunction with an enhancement of chirality in the solid state. l-Alanine with 98 % ee was synthesized from the (S)-amine by using the method discussed here. Achiral aromatic and heteroaromatic aldehydes could also be successfully utilized to afford chiral α-aminonitriles in a highly stereoselective manner. The stereodivergent synthesis of styrylglycine nitriles has also been accomplished by using racemic and enantioenriched 2-methylbenzhydrylamine. Thus, accompanied with a small rearrangement of the common substrate from achiral toward chiral, the present reactions induce an enhancement of chirality, and expands the concept of stereoselective synthesis to increase the opportunity to access highly enantioenriched compounds such as α-amino acids.

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Section: Resultsmentioning

confidence: 95%

Highly Stereoselective Strecker Synthesis Induced by a Slight Modification of Benzhydrylamine from Achiral to Chiral

Takamatsu

Aiba

Yamada

et al. 2017

Chemistry A European J

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“…H + /Dean-Stark, MgSO 4 , CuSO 4 ) affording low/trace yields. Investigation of an extensive range of R-substituents in 9 [14] indicated that the tert-butyl 'dummy group' was superior to all others for the following reasons -(i) While the SO 2 NHBu t group is easily removed under the same conditions as 4 deprotection [10] (mild pyridine reflux with 5% w/w water) the compounds are hydrolytically robust in routine usage (much more so than the methyl derivatives 9a-b).…”

Section: Synthesis Of Sulfamyl Imine Acceptorsmentioning

confidence: 99%

“…All of the compounds had properties identical to materials provided by our previous deprotections of 4. [10] Summary conditions for the ee determinations are given in the Experimental Section (Table 4). [a] Reactions were carried out using isolated samples of 10 prepared from 9 (0.5 mmol).…”

Section: Deprotection Of Sulfamide Addition Products 10mentioning

confidence: 99%

“…[10,14] All reactions involving air sensitive materials were carried out under argon using standard Schlenk techniques. Ligands L A -L B were commercial products or prepared by literature procedures.…”

Section: Generalmentioning

confidence: 99%

“…[n9] In seeking to balance the requirements of imine activation, protecting group stability and ease of removal we have suggested that the use of a simple -SO 2 -function can be effective, as in 4, that can be removed under mildly basic conditions (5% water in pyridine) -conditions complementary to groups A-D. [10] However, the presence of two stereocentres in 4 complicates their ee assay. To avoid such issues we proposed that the use of a simple 'dummy' amine in the sulfamoyl group -SO 2 NHR should prove useful.…”

Section: Introductionmentioning

confidence: 99%

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