2005
DOI: 10.1021/jo050188a
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Stereoselective Addition of the Titanium Enolate of N-Acetyl (4S)-Isopropyl-1,3-thiazolidine-2-thione to Five-Membered N-Acyl Iminium Ions

Abstract: [reaction: see text] Addition of the chlorotitanium enolate of N-acetyl 4-isopropyl-1,3-thiazolidine-2-thione to five-membered, N-substituted N-acyl iminium ions furnished the corresponding Mannich-type addition products with good diastereoselectivity and in good yields. The synthetic utility of the addition product 8 was demonstrated in a chemospecific anti-aldol reaction with cinnamaldehyde. By using this strategy, we constructed three contiguous chiral centers with high stereocontrol employing the same chir… Show more

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Cited by 25 publications
(7 citation statements)
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“…The reaction is catalytic in magnesium salts and is facilitated by silylation with chlorotrimethylsilane at room temperature. We reported this anti -aldol reaction when the aldehyde employed was cinnamaldehyde and the N -acyl thiazolidinethione was the addition product of the titanium(IV) enolate of N -acetyl-4 S -isopropylthiazolidinethione with N -crotyl-5-acetoxy pyrrolidinone . An X-ray crystallographic analysis confirmed the stereochemical output of the reaction.…”
mentioning
confidence: 77%
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“…The reaction is catalytic in magnesium salts and is facilitated by silylation with chlorotrimethylsilane at room temperature. We reported this anti -aldol reaction when the aldehyde employed was cinnamaldehyde and the N -acyl thiazolidinethione was the addition product of the titanium(IV) enolate of N -acetyl-4 S -isopropylthiazolidinethione with N -crotyl-5-acetoxy pyrrolidinone . An X-ray crystallographic analysis confirmed the stereochemical output of the reaction.…”
mentioning
confidence: 77%
“…We recently reported the stereoselective addition of the titanium(IV) enolate of N -acetyl-4 S -isopropylthiazolidinethiones to cyclic N -acyl iminium ions . Addition of a metal enolate derived from N -acetyl thiazolidinethione to a cyclic N -acyl imine creates a stereocenter with stereochemistry opposite of the one obtained when added to an N -acyl iminium ion using the same chiral auxiliary. , Because N -acetyl-4 R -isopropylthiazolidinethione would be too costly to prepare, we selected the 4 R -phenyl thiazolidinethione 5 for the construction of the required stereochemistry of C9a as found in natural stemoamide (Scheme ).…”
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confidence: 99%
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“…[32] The addition of chlorotitanium enolates of N-acetyl IPTT 4 to five-membered N-acyl iminium ions was investigated (Scheme 5). [33] The anti-addition product 14 was selectively obtained when two equiv. of TiCl4 and 1.2 equiv.…”
Section: Addition On Iminium Ions and Natural Products Synthesismentioning
confidence: 99%
“…There has been a growing interest in the use of chiral 1,3-thiazolidine-2-thione and 1,3-oxazolidine-2-thione auxiliaries in several asymmetric transformations because they are easy to prepare, promote high diastereoselectivities, and are easier to cleave than more common oxazolidinone analogues. , These thiocarbonyl-containing chiral auxiliaries have been particularly useful in the acetate–aldol reaction where chiral oxazolidinones failed to give any diastereoselectivity . In addition, three of the four possible propionate–aldol products can be accessed from the same chiral thiazolidinethione, only by modifying the number of base-equivalents or the nature of the Lewis acid …”
mentioning
confidence: 99%