Pfizer — US 4,041,163
"The pyrimido[2,1-b]benzothiazole ring system was first reported by Antaki, et al., J. Chem. Soc., 551 (1951)."
The following are selected examples of how independent third parties described the work of H. B. F. Antaki — patent attorneys writing under legal obligation to accuracy, review authors summarising the state of a field, encyclopaedia editors, and researchers building on his chemistry. None had any obligation to mention him. These are their words, not ours.
Patent text is in the public domain. Every word in a patent filing is deliberate, reviewed by attorneys, and legally consequential.
"The pyrimido[2,1-b]benzothiazole ring system was first reported by Antaki, et al., J. Chem. Soc., 551 (1951)."
"The synthesis of a 1H-pyrimido[1,2-a]quinoline appears to have first been reported by Antaki et al., J. Chem. Soc., pp. 551–555 (1951)."
Followed by a paragraph-by-paragraph summary of both the 1951 J. Chem. Soc. and 1958 J. Am. Chem. Soc. papers, closing with: "The compound demonstrated antischistosomal action."
Cites 1951 J. Chem. Soc. and 1958 J. Am. Chem. Soc. Uses the word "first" in the Description of Prior Art. Israeli counterpart IL49924. Filed within weeks of a Bristol-Myers patent citing the same two papers.
"Some examples of the acrylates of formula VI… are disclosed by Antaki in J. Amer. Chem. Soc., 80, 3066 (1958)."
Antaki 1958 listed first in the description of the synthetic method. The examiner independently placed Antaki 1958 on this patent's record (asterisk-cited).
"Some examples of the acrylates of formula VI are disclosed by Antaki in J. Amer. Chem. Soc., 80, 3066 (1958)."
Listed first; Nishigaki 1971 listed second.
"Thiazolo[3,2-a]pyrimidinones and pyrimido[2,1-b]benzothiazolones have been previously described by… Antaki, et al., J. Chem. Soc., 551 (1951)…"
Antaki cited among the foundational prior art. The patent's novelty claim rests explicitly on what none of those references had disclosed.
"The compounds of formula I wherein R is 5-nitro-2-furyl, 3-nitrophenyl and 4-nitrophenyl are known, for example from… Antaki, J. Chem. Soc., 4877 (1963)."
"Suitable reaction conditions are also reported by Antaki in J. Chem. Soc., 4877 (1963)."
The patent cites four non-patent references in total; Antaki 1963 is cited twice within it, for the compounds and for the conditions. The same patent family cites him again in EP 0539153.
"Suitable reaction conditions are also reported by Antaki in J. Chem. Soc., 4877 (1963)."
Antaki 1963 appears in the Non-Patent Citations, marked with an asterisk — examiner-supplied, not applicant-supplied.
"hexahydroquinoline derivatives aroused our interest."
Friedrich Bossert and Wulf Vater, inventors of nifedipine. Reference 7 in that paper is Antaki, J. Chem. Soc., 1963. He appears again as reference 13, alongside the classic Hantzsch and Knoevenagel reactions.
"In 1951 Antaki and Petrow came to the conclusion that the poor yield of the pyrido[1,2-a]pyrimidines in the reaction of 2-aminopyridines and acylacetates is ascribed to a rearrangement reaction that the intermediate 2-acylacetamidopyridines undergo."
"Products of 4-methylpyridine and ethoxymethylene cyanoacetate in various ring closure reactions were first described by Antaki."
"Antaki concluded that the absorption band for the 2-oxo-2H- and 4-oxo-4H-pyrido[1,2-a]pyrimidines in the range 300–400 nm can be ascribed to the 2-imino-1-substituted-1,2-dihydropyridine chromophore, and the band in the interval 250–270 nm to the C=C–C=O chromophore of the molecules."
The canonical review of pyrido[1,2-a]pyrimidine chemistry. Antaki appears in the running text across multiple pages, not only in the reference list.
"Antaki and Petrow showed that the product was in fact the 2-methyl-4-keto isomer… by virtue of its alternate synthesis from 2-bromopyridine and ethyl β-aminocrotonate."
Received October 3, 1968. Antaki and Petrow appear as reference 15 in the paper's numbered bibliography, alongside Khitrik, Adams and Pachter, and Lappin.
"Earlier synthetic work by Khitrick, Antaki and Petrow, and uv spectral studies by Adams and Pachter, had clearly established that the reaction of 2-aminopyridine… gave 2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one."
"That his structure assignment was incorrect and that the product was the isomeric 4H-2-methylpyrido[1,2-a]pyrimidin-4-one… was established by Antaki and Petrow, who, in addition to reproducing Khitrick's synthesis, reported that except for that procedure, all other attempts to convert 1 to 2 or 3 were unsuccessful."
"2-Aminothiazole reacted with acetoacetic and β-aminocrotonic esters… to give the appropriate 5H-pyrimido[2,1-b]thiazol-5-ones instead of the 7-oxo derivatives which were incorrectly assigned previously."
Cites Antaki and Petrow's 1951 paper as the precedent for this route.
"Antaki and Petrow discovered that when ethyl β-aminocrotonate was heated with 2-bromopyridine, a cyclized compound was obtained… Antaki formulated their product as 2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one."
"Employing the procedure given for the 4-one derivative reported by Antaki and Petrow," and confirmed by mass, NMR, IR and UV spectra that the product was the 4-one, against a contrary proposal published in 1969.
"Antaki and Petrow discovered that when ethyl β-aminocrotonate was heated with 2-bromopyridine at 180–200° for several hours, a cyclized compound was obtained… Antaki and Petrow formulated their product as XVII."
"Ultraviolet Spectra and Structures of the Pyrido[1,2-a]pyrimidones." Within a year of the 1951 paper, confirmed the structure by ultraviolet spectroscopy: "Antaki and Petrow synthesized XVII in good yield by heating 2-aminopyridine with ethyl β-aminocrotonate."
Antaki 1958 J. Am. Chem. Soc. is listed as Reference 1(a) in the entry for Ethyl Ethoxymethyleneacetoacetate. DOI: 10.1002/047084289X.re082
Reference 8 in the paper body and Table VIII footnote e: compounds were prepared using the Antaki & Petrow procedure.
Surveying the literature on 4-azabenzo[c]quinolizine derivatives, the authors cite two prior compounds in the class: Antaki & Petrow 1951 and Antaki 1958.
"Of a series of quinolino-, indolo-, pyrrolo-, thiazolo- and triazafluoreno-steroids prepared as potential antimicrobial agents… (Antaki and Petrow, 1951)."
"The practicality and elegance of the Antaki synthesis, particularly its one-step approach, make it highly relevant not only from a historical standpoint but also for contemporary medicinal chemistry and drug discovery applications. It was therefore important to recognize his work alongside other foundational methods in the field."
Written in personal correspondence after the publication of Oduselu et al., Frontiers in Chemistry, 2026 — the paper that formally names the Antaki synthesis as a classical multicomponent reaction alongside the Hantzsch and Stankevich methods. DOI: 10.3389/fchem.2026.1769586